Find out more about our subscriptions
As it happened: Test day four
By Matt Beer, Glenn Freeman and Scott Mitchell
The live commentary has ended. No further updates will be posted.
07:43 Good morning from Barcelona - which this morning is looking almost as gorgeous as Devon. It's time for test two, day four of Formula 1 2015.

Barcelona looks like DEVON

07:47 News of a driver plan tweak already this morning - Fernando Alonso and Jenson Button will share the McLaren today.

07:49 McLaren: "Our drivers will be sharing duties today, with Fernando in the car first and JB taking the reins this afternoon."

07:51 BEN ANDERSON: McLaren's reshuffle is to ensure balanced feedback by giving the drivers equal mileage.

Alonso has managed rather more running than Button this week, with the Spaniard's day being the one where things ran relatively smoothly while Button has had the brunt of the MGU-K seal woe.

That didn't stop him being optimistic about winning this year, though:

Button: McLaren might win by end of 2015

07:52 Here's the full expected line-up today:

Mercedes: Nico Rosberg
Red Bull: Daniil Kvyat
Williams: Valtteri Bottas
Ferrari: Sebastian Vettel
McLaren: Fernando Alonso/Jenson Button
Force India: Nico Hulkenberg (2014 car)
Toro Rosso: Carlos Sainz Jr
Lotus: Romain Grosjean
Sauber: Felipe Nasr

07:54 Temperatures today are already 7.2 degrees C in the air and 10.6 on track, and it took till lunchtime to get there for most of this week.

Many teams are expecting that today will be the day to get good representative work done this week given the 'just right' weather conditions expected.

Bit breezy though, wind speed is currently 13km/h south-westerly.

Helmet07:57 Force India reveals that Hulkenberg has even got a perky weather forecast on his helmet:

"His helmet leaves little doubt on the kind of weather we're expecting!"

07:57 Honda on its plan for McLaren today:

"Time to give the power unit a final run with more testing. Stability is the main focus for today."

07:58 Yesterday, Pastor Maldonado and Max Verstappen used super-soft tyres to battle for the top spot, while many others did race runs. Sebastian Vettel visited the gravel and McLaren-Honda had more frustration.

Here's the full recap:

Barcelona Saturday test report

08:01 Bottas, Vettel, Sainz and Grosjean are first out as Sunday begins.

08:01 Extensive revving from the Red Bull garage suggests Kvyat won't be far behind.

08:02 Hulkenberg makes his first on-track appearance of 2015 (in an F1 car not a Porsche LMP1 at least) too.

08:02 Kvyat and Rosberg set off too.

08:05 Nasr gets Sauber's morning under way. Only car not out yet is the McLaren, though the crew has been out doing pitstop practice.

08:09 There was a bit of excitement last night when Red Bull's truck appeared in the pitlane doing what appeared to be a very comprehensive packing-up job.

It looked like the mechanics were just clearing away anything not needed for today, but as more and more equipment was loaded, there was a brief moment of wondering 'is Red Bull going home...?'

The team later confirmed that it was just getting an early start on its get-out and clearing away all the pitstop equipment it won't be using today as it's done all its pitstop practice and race work already.

So where yesterday there was a full Red Bull 'prat perch' set-up on this wall, today there's just a lonely single box.

As far as we can see from here, the only teams with a full pitwall set-up out at present are Toro Rosso and Ferrari.

08:10 That doesn't mean we won't see any significant work today, though, as teams just differ in how extensive their pit arrangements are in testing.

Valtteri Bottas hinted last night that Williams may well attempt a race simulation today, and with conditions looking both appealing and consistent, others are likely to feel it's a good time for representative runs too.

08:12 Nothing representative as yet of course. Kvyat has done three out/in-laps, Bottas and Rosberg two each, Vettel, Sainz, Grosjean, Hulkenberg and Nasr one each, and nothing from Button so far.

08:15 Lotus has led two of the three days this week so far. It has gone for more performance-based runs than many other teams, but Pastor Maldonado made clear yesterday that running super-softs wasn't an attempt to grab headlines.

He said after last winter's problem-filled misery, Lotus was just thrilled to have such good reliability that it had time to whizz through all the tyre compounds at this relatively early stage.

"They're not the best here, they are too soft for this kind of track," he admitted.

"But with a soft tyre we did a very good laptime and we found a very good balance, which is quite encouraging for the team.

"It was very important for us to work through the tyres and learn from the tyres how the car reacts to the different compounds, even if they are not the right one for here.

"We have them available and I think you need to use them for mileage and for experience. Everything was going quite well and we decided to go through them."

What will Grosjean try today? Here he is heading out into a sunshine a few minutes ago.

Romain Grosjean, Lotus, Barcelona F1 testing February 2015

08:16 Just one car out on track now, with Rosberg running for Mercedes, but it sounds like Sainz's Toro Rosso is about to join him.

08:17 Rosberg sets today's first laptime: a 1m36.999s.

08:19 An improvement to 1m36.200s for Rosberg, while Kvyat and Grosjean come out too.

08:20 Sainz clocks a 1m37.232s for his first lap.

08:23 Five cars on track but most coming in and out of the pits, or running slowly - like Grosjean's Lotus, which laps in 2m12.7s.

08:24 We have our first red flag of Sunday.

08:25 Rosberg's Mercedes is parked in the gravel, looks like he's gone in backwards.

08:26 Here's a look at the beached Mercedes from the circuit cameras:

Nico Rosberg, Mercedes, goes off, Barcelona F1 testing February 2015

08:27 Rosberg has gone off at Turn 5, and is now surrounded by marshals and recovery vehicles.

08:28 On the circuit CCTV, the Mercedes went through the first few corners following Grosjean's Lotus closely. No hint of any contact or incident (though it wouldn't be the first time this week we'd had a testing collision), but does raise the possibility of a passing attempt or misunderstanding.

08:29 The Mercedes is now sheeted-over and being lifted onto the recovery truck. That's the same gravel trap Vettel put the Ferrari in yesterday.

08:30 Very early lap tally:

Rosberg 8
Sainz 6
Kvyat 5
Grosjean 4
Hulkenberg 3
Vettel 1
Nasr 1
Alonso 0

08:34 The truck and recovery vehicles are now pulling away from Turn 5 and heading pitward, while Rosberg - helmet still on - has had a lift back.

08:37 Back to green and Nasr is first out.

08:38 Grosjean follows him, which suggests that even though Rosberg was near the Lotus when he went off, he didn't use it as a launchpad or anything like that. There was certainly no obvious sign of damage on the Mercedes.

08:39 Vettel's Ferrari sets off too.

08:41 Now the camera has panned out to give a better view of the marks in the gravel, it looks like Rosberg just lost it mid-corner at the tight downhill left-hander.

08:41 Grosjean is straight back in, while Nasr and Vettel stay out, with Kvyat joining them.

08:42 Vettel puts in our first proper laptime of the day as he does a 1m31.990s, quickest by 4.2s so far.

08:43 Vettel improves by four tenths to a 1m31.562s.

08:44 Mercedes explains Rosberg's rotation: "Cold track, cold tyres, a simple spin for @nico_rosberg. A few high tech (ahem) gravel hoovers required but no major dramas to report."

08:44 Vettel quicker again on a 1m31.332s.

08:46 Staying out on medium tyres, Vettel finds another second and does 1m30.363s.

08:48 Nasr's Sauber stopped at the pit entry on his last run and had to be collected by his mechanics.

As they pushed him down the pitlane, they had to stop briefly while Kvyat's Red Bull came in and dodged around them.

The Sauber sat in the pitlane waiting alongside Kvyat while he paused in his pit bay for a quick check, then continued in its way once the Red Bull had set off again.

Felipe Nasr

08:50 Our colleagues at XPB were on the spot where Rosberg had his spin at Turn 5, so here's a picture of him arriving backwards in the gravel:

Nico Rosberg, Mercedes, goes off, Barcelona F1 testing February 2015

08:52 Rosberg's car is quickly dusted down and back out though, and he does a 1m33.627s to go second.

08:54 Bottas has also returned to the track and his first flying lap is a purple-inducing 1m28.868s. The Williams goes straight to top spot.

08:55 Rosberg improves his time but stays third.

Bottas lowers the benchmark further to 1m28.449s.

08:55 Here's Rosberg's spin in full, courtesy of XPB. You could print these out, cut them out and make a little animated flip book with them if you want...

Nico Rosberg, Mercedes, goes off, Barcelona F1 testing February 2015

And they'll be on their way into our gallery from the F1 test shortly too.

08:56 Back on track, Rosberg improves to 1m32.653s, staying third.

08:58 A very slight improvement from Rosberg, up to a 1m32.618s.

08:58 Bottas has stayed out, running on mediums, and after a slower 1m30s lap, he now does a 1m29.555s.

08:58 A very slight improvement from Rosberg, up to a 1m32.618s.

08:59 Lap count so far

Rosberg 14
Vettel 8
Kvyat 8
Bottas 7
Sainz 7
Grosjean 7
Hulkenberg 3
Nasr 3
Button 0

09:00 Early headlines:

* Bottas and Vettel set the initial pace
* Rosberg spins into gravel on cold tyres but soon rejoins
* McLaren still confined to the garage

09:01 Lap count by engine:

Mercedes: 31
Renault: 15
Ferrari: 11
Honda: 0

09:03 Nico Hulkenberg pops in the first Force India flying lap and goes third with a 1m31.251s, 2.8s behind Bottas.

09:03 Vettel improves in second place and cuts Bottas's advantage to 0.8s.

09:04 Hulkenberg improves as well. He stays third but has now done a 1m30.221s, 1.7s off the pace.

09:05 Vettel keeps striding closer to Bottas's first place, cutting the gap to half a second now.

Expect the German contingent in the press room to start yelling to their Finnish counterpart shortly - though the best of that banter is saved for the Raikkonen days.

09:12 F1's two Nicos - Hulkenberg and Rosberg - make very small improvements to their times and stay third and fourth. Both are out on mediums.

09:13 Hulkenberg now comes into the pits, as Vettel did on the previous lap, while Grosjean is on potentially Lotus's first proper lap.

09:13 A 1m32.685s for Rosberg, 0.082s off his best.

09:15 A 1m27.991s from Sainz on soft tyres thrusts Toro Rosso to the head of the times.

09:16 Grosjean also improves, with first a 1m31s then a 1m30.710s to bring him ahead of Rosberg for fifth.

09:19 Grosjean eventually got down to a 1m29.362s on that run, placing him fourth between Vettel and Hulkenberg. He was running on mediums.

09:24 As BEN ANDERSON is an F1 paddock regular, he's been roaming the pitlane for most of the week chasing up exclusive info, quotes, tip-offs and insight.

That's all very well (as his exclusive interviews with those in the know at McLaren/Honda and Renault this week have gone down well), but there are other bonuses to being well-connected in F1 that the Live commentary crew felt he wasn't taking proper advantage of.

So today he's been tasked with bringing us free biscuits. And plenty of them. And coffee.

And he's doing well:


09:25 Lap count so far:

Rosberg 22
Sainz 19
Vettel 16
Grosjean 16
Bottas 14
Hulkenberg 12
Kvyat 14
Nasr 3
Alonso 0

(We're chasing McLaren info)

09:26 Times so far:

1 Sainz 1m27.991s (softs)
2 Bottas +0.456s (med)
3 Vettel +0.979s (med)
4 Grosjean +1.371s (med)
5 Hulkenberg +1.930s (med)
6 Rosberg (+4.612s)

09:28 We mentioned Nasr's Sauber being pushed down the pitlane earlier, here's some (not massively specific) info from the team:

"We have general issues with the #C34. The team is investigating and we will be back on track as quickly as possible."

Felipe Nasr, Sauber, Barcelona F1 testing, February 2015

09:31 Sauber had a tough Saturday too, with Marcus Ericsson sitting out most of the morning due to gearbox problems.

He put an upbeat slant on it last night...

"Just some small things with the braking and the entry of the corners. The car didn’t really do what we expected. But yeah I’m sure it’s not a big problem. I think every team has days like this."

...but it's fair to say that after showing signs of genuine improvement at Jerez, this isn't such a strong week for Sauber.

No one expected the team's time-topping performances at Jerez to accurately reflect the pecking order, but there was definitely a sense there that things were looking brighter than in the point-less 2014 season.

09:31 All quiet at Barcelona now with everyone back in the pits.

09:35 So used to seeing mechanics with special safety gloves to deal with ERS these days that when someone walks past with rubber gloves on you tend to assume they're from an F1 team. But this lady is carrying a mop and bucket as well so does appear to be an actual cleaner.

09:35 Hulkenberg brings the Force India back out.

09:37 Many have wondered how worthwhile this week is for Force India as its 2015 car still isn't ready yet (its debut is now intended for next week's final test).

Sergio Perez insisted earlier in the week that being here is definitely important because of the chance to understand the 2015 tyres, and that even though it's basically last year's car, there are enough 2015 parts on it to still learn things.

But he did add:

"We have to look at the positives and there are plenty of positives and we are just waiting for the new car.

"Hopefully the new car turns up and we can do some proper mileage with the new car."

09:38 Hulkenberg improves his time to a 1m29.081s and moves ahead of Grosjean into fourth.

09:39 "Ooh Vettel!" is the call from our German friends, and rightly so - he's just gone fastest on a 1m27.474s, half a second ahead of Sainz.

09:39 Hulkenberg improves again too, but stays fourth on a 1m28.764s.

09:40 That new top time from Vettel was set on mediums. Second-placed Sainz is the only man whose pace has come from softs so far today.

09:41 Rosberg jumps to third on a 1m28.216s on the medium-shod, gravel-free Mercedes.

09:43 Rosberg improves to a 1m28.175s with a lap that included the best final sector of the day so far.

09:43 The Mercedes is now 0.7s off Vettel's leading pace.

09:44 Grosjean nips ahead of Rosberg into third for Lotus on a 1m28.042s, but the Mercedes is improving again.

09:44 McLaren tells BEN ANDERSON it'll be on track in 40 minutes. No reason given for its delay.

09:45 Rosberg does a 1m27.790s to move into second, three tenths down.

09:45 Grosjean, who is running on mediums again, shaves 0.013s off his time but stays 0.038s behind Sainz in fourth.

09:46 Rosberg improves again, to a 1m27.663s, and is now 0.189s off Vettel at the front.

09:48 More from McLaren on why it's not out yet:

"The new part arrived late last night so we needed time for the power unit to be configured."

09:49 That new part at McLaren is the re-engineered MGU-K seal that it hopes will solve the problems that have plagued Honda all week.

09:51 Latest lap count:

Rosberg 30
Vettel 24
Sainz 23
Grosjean 23
Hulkenberg 18
Kvyat 17
Bottas 16
Nasr 3
Alonso 0

09:52 Sainz puts Toro Rosso back on top wit a 1m27.236s lap, two tenths better than Rosberg. Off to the window to check his tyres...

09:52 Sainz is running on soft tyres again for that lap.

09:52 Lap count by engine:

Mercedes 87
Renault 40
Ferrari 27
Honda 0

09:53 Bottas makes a three-tenth improvement in fifth place, nine tenths off the pace. He's running just ahead of Sainz on track.

09:54 Times so far;

1 Sainz 1m27.236s
2 Vettel +0.238s
3 Rosberg +0.427s
4 Grosjean +0.793s
5 Bottas +0.935s
6 Hulkenberg +1.528s

09:54 All those times have been set on mediums except Sainz, who ran softs.

09:54 Kvyat has been out a lot but yet to do a flying lap. Nasr's Sauber didn't do one before it ran into problems and Alonso is yet to emerge.

09:56 Headline summary:

* Sainz uses softs to set pace
* Vettel, Rosberg, Grosjean, Bottas closely-matched in second to fifth on mediums
* Rosberg quickly back on track after spinning into gravel early on
* Nasr parks his Sauber in the pit entry with mechanical problems
* Delay getting Honda engine ready after arrival of crucial new MGU-K seal means Alonso misses first two hours and counting

09:59 The McLaren emerges, Alonso doing an out-lap on soft tyres.

10:01 More on Toro Rosso from BEN ANDERSON as pacesetter Sainz continues round in 1m31.2s on his now fading softs.

The Renault powered teams suffered a disastrous pre-season 12 months ago and a difficult start to 2015 at Jerez, but reliability has improved massively since then.

Red Bull has managed two race runs over the past two days with Daniel Ricciardo and Daniil Kvyat, while Toro Rosso rookie Max Verstappen clocked 129 laps yesterday - more than any other driver that day.

Toro Rosso technical director James Key told AUTOSPORT: "Progress since Jerez is good as we are able to set up the car with more options at Barcelona and we also got some interesting direction from Jerez to test this week.

"Reliability is ongoing and part of winter testing, but mileage covered yesterday was positive.

"Renault is making progress and we look forward to further steps during the last test next week."

Carlos Sainz Jr, Toro Rosso, Barcelona F1 testing February 2015

10:07 It's gone quiet again for a moment, but now Vettel reappears in the Ferrari.

10:09 After lighting up the timing screens at Jerez, this has been a quieter week for Ferrari so far, but Vettel's smile was fully on display last night and Raikkonen was... well, he was quite Raikkonen-esque to be honest on Thursday and Friday but that doesn't mean he wasn't happy.

Here's Vettel's summary yesterday evening:

"People like myself and Kimi are happy with initial car behaviour. There is still a long way to go and Mercedes are the ones to beat.

"Those are the facts, I would say."

10:10 Vettel sets the fastest middle-sector time and improves to within just 0.002s of Sainz's benchmark.

10:10 Vettel is running mediums still, whereas Sainz's time came on softs.

10:10 Alonso and the McLaren are back out and potentially beginning a run.

Fernando Alonso, McLaren, Barcelona F1 testing February 2015

10:12 Alonso's first flying lap is a 1m30.427s, slowest so far but at least McLaren-Honda's day has begun.

10:13 Alonso continues round, does a 1m28.364s and slots ahead of Hulkenberg into sixth. The McLaren is on mediums.

10:14 Vettel's run, which began with that 1m27.2s, is now in mid-1m28s.

10:15 Kvyat is still in and out of the pits. No tyre changes (Red Bull's long since packed that kit away), but adjustments and checks with sensors and other equipment every time he pops into the pit bay.

10:16 A little quicker for Alonso next time, 0.056s better than his previous lap. And now the McLaren comes in. Six laps done in total.

10:17 Lap count latest:

Sainz 38
Rosberg 34
Vettel 30
Grosjean 23
Bottas 23
Kvyat 23
Hulkenberg 18
Alonso 6
Nasr 3

10:18 Force India tweets info on the plan from its chief race engineer Tom McCullough:

"The main focus of today's work is to allow Nico to have an in-depth assessment of the new 2015 tyres, together with mileage."

10:19 After 23 out/in/out/in/out/etc-laps, Kvyat does a time of 1m42.118s to get on the board for Red Bull.

10:19 Kvyat improves to 1m34.031s next time through.

10:20 So everyone has now set a time of sorts bar Nasr, whose Sauber was halted by "general issues" early this morning.

10:24 Rosberg goes quickest, still on medium tyres, as he pas in 1m27.142s to pip Sainz by 0.094s.

10:25 We've got a top three covered by 0.096s now.

10:25 Rosberg is going faster still on his next lap.

10:25 Sainz is running on older softs, now in 1m31s, and Bottas has taken to the track with hards, lapping in 1m29.3s.

10:26 Rosberg was faster in the first two sectors, but his final part of the lap wasn't so great, making him 0.115s slower by the finish line.

10:27 Rosberg takes great speed into Turn 10, reports SCOTT MITCHELL from trackside. His rotation point is a good deal further into the corner than Sainz, for example, who takes a much more conventional racing line. Bottas just spanks the inside kerb!

10:28 More from SCOTT MITCHELL out at a windy Turn 10-13: Sainz and the Toro Rosso looks very comfortable, and super-smooth.

10:32 Both Rosberg and Vettel are lapping in low 1m28s on medium tyres at the moment, though they started their runs at different times so might not be possible to do a direct comparison.

10:34 Rosberg's times have now gone out to high 1m28s, while Vettel dipped into a high 1m27s before going back to low 1m28s.

10:34 Alonso is running again in the McLaren.

10:38 So it's a good time to bring you SCOTT MITCHELL's analysis of the sound of the engines after his time at trackside:

The Honda sounds awful off-throttle. The Renault is the quietest of the three.

The Ferrari seems to put the power down quite well, not entirely smoothly, though.

It's sort of a middle ground between the Renault and Honda in terms of the noise as the throttle is applied.

It's when Alonso puts the power down that there's an odd interim noise before 'full' power. It's hard to describe, so we'll stick with 'unrefined'.

The transition through the notes is smoother with the Renault, as you'd expect. Even when Alonso looks like he's starting to push and gets on the throttle earlier mid-corner, the Honda sounds quite rough.

10:38 Alonso improves on his first two sectors but it was slower at the end and the lap falls two tenths short of his best.

Fernando Alonso, F1 testing 2015

10:41 More engine noise thoughts from SCOTT MITCHELL, as Hulkenberg moves the Force India up to fourth on a 1m27.561s:

The Mercedes is much louder than the Force India - is that a new, noisier spec for 2015? The Williams certainly has the same note.

10:43 Hulkenberg goes a bit quicker in the first sector, then pits, In fact, everyone has finished their runs and pitted, so time to recap.

10:44 Headlines so far:

* Rosberg on mediums pips Sainz on softs to the top time by 0.094s.
* Vettel also within 0.096s of first place.
* McLaren joins late after new engine parts arrive overnight. Alonso is seventh after 12 laps.
* Rosberg spins off on cold tyres early on but is soon running again.
* Nasr confined to the Sauber pits with mechanical problems.

10:45 Lap count:

Rosberg 46
Sainz 45
Vettel 38
Bottas 35
Grosjean 32
Hulkenberg 26
Kvyat 26
Alonso 12
Nasr 3

10:46 Times so far:

1 Rosberg 1m27.142s
2 Sainz +0.094s
3 Vettel +0.096s
4 Hulkenberg +0.419s
5 Grosjean +0.887s
6 Bottas +1.029s
7 Alonso +1.166s
8 Kvyat +6.889s
(no time for Nasr)

10:47 Lap count by engine:

Mercedes 139
Renault 71
Ferrari 41
Honda 12

10:49 Vettel ends a quiet spell and sets off again in the Ferrari.

10:50 The temperature's stabilised at a comfy 11 degrees C outside, cooled by the 13km/h wind, while with the sun out the track temperature is up to 22.2.

Want the full set of weather screen numbers? OK then, humidity is 29 per cent and barometric pressure is 1004.7mb.

10:51 Good start to Vettel's lap - he's fastest so far in sector one.

10:52 That's Vettel's first run on softs today and it puts him quickest by six tenths of a second with a 1m26.454s.

10:55 Sainz immediately responds - also running soft tyres he goes 1.7s faster than his previous best and reclaims first place by 0.770s.

10:55 That's a 1m25.674s for Sainz, while Vettel's next laps are a 1m26.9s and a 1m27.2s.

10:55 Rosberg, still on mediums, improves to a 1m26.798s but stays third.

10:56 The circuit cameras catch Vettel paying a quick visit to the Turn 1/2 run-off so this lap will be a bit deceptive.

10:56 Rosberg is 0.016s quicker than before, improving his time to a 1m26.782s and staying third.

10:57 Sure enough Vettel clocks in at 1m34s, while that did seem like a proper qualifying-style lap for Sainz as he backs right off afterwards.

10:57 Sainz pushes again, but it looks like the best of the tyres is gone as he does a 1m27.0s.

10:58 We've had a few readers asking what specification Mercedes engine Force India is running, and can confirm it's still the 2014 version.

10:58 Just a short run for Vettel too and he's now back into the pits.

11:01 Kvyat is running again for Red Bull.

As well as its garage being beneath our feet, its trucks are right next to the walkway into the media centre, so we get to snoop into its business quite often.

We haven't seen anyone using these sofas all week. They definitely look comfy so either it's too cold out there or those (and this is unlikely) are officially Red Bull's 'sofas of success' and you only see Christian Horner lounging on them when he's confident Renault is matching Mercedes' horsepower.

Red Bull sofa

11:03 Still yet to see Red Bull really get involved at the sharp end today, and though Kvyat improves on that lap, it's only a 1m32.890s, still 7.2s off the pace.

He wasn't flat-out down the straight and is running on winter hards.

11:05 Minor time correction: Sainz's top spot lap is a 1m25.684s not a .664s as we initially noted. That's entirely down to appalling eyesight.

11:07 Now Kvyat gets faster with a 1m30.146s, while Hulkenberg improves a little with a 1m27.241s. Neither changes position.

11:07 Another improvement from Kvyat, now up to a 1m29.982s and 4.2s off the pace.

11:09 Back out on softs, Sainz improves his sector one time but the rest of the lap isn't so great.

11:09 Meanwhile Kvyat and his winter-hard-shod Red Bull find another two tenths in eighth place.

11:09 Vettel now sets a middle-sector best on soft tyres...

11:10 But sectors one and three aren't so good for the Ferrari and he doesn't improve.

11:10 The spectators brought into the media centre as part of their paddock tour look like seeing journalists is absolutely the highlight of their day. And none of them are offering biscuits.

11:11 Sainz is straight back into the pits after that single flying lap on softs.

11:12 Less than an hour to go until lunchtime, and those of you who have been with us this week have probably noticed that we like to keep you entertained for that hour by inviting your contributions on a topic from F1's history.

So far we've discussed helmet designs and car liveries, and today we want to hear what your favourite Grand Prix of all time is. To put it another way, if Bernie Ecclestone made every F1 race available to watch on an online database, which would you choose first (you're allowed to choose ones that FOM doesn't have the footage of as well!).

Let us know using #autosportF1 on Twitter and we'll get through as many as we can while our paddock team hunts out food in Spain.

11:15 On the subject of our liveries discussion yesterday, one car that received quite a few nominations but didn't get included yesterday was the 2009 world championship-winning Brawn GP.

So here it is, and to make it remotely relevant we've gone for a shot from the Barcelona pre-season test of that year where the blistering pace of the car first became apparent.

Jenson Button, Brawn GP 2009

11:15 On track now, we have Vettel on softs with times tailing off to low 1m29s, Bottas doing high 1m29s on hards, and Alonso and Grosjean pitting after short appearances on mediums.

11:16 Vettel now comes in, so just Bottas running.

11:16 Williams is a bit of a dark horse at the moment, yet to really show its hand - although we'll get more details of exactly what it's up to from Rod Nelson tonight.

11:17 Yesterday Williams was happy to devote pretty much the whole day to pitstop practice - partly because, as Bottas explained, it didn't want to go into "fine details of set-up" until the next upgrade package arrives in the coming week, and also because after letting a few results slip in the pits in 2014, the team wanted to make sure it was absolutely operationally sharp going into 2015.

11:20 Lots of 66th birthday wishes to three-time world champion and Mercedes co-chief Niki Lauda today, so as AUTOSPORT's offering, here's a icture of him winning the 1974 Spanish Grand Prix at Jarama - his maiden F1 win and the launchpad for his game-changing stint at Ferrari.

Niki Lauda, Ferrari, Spanish GP 1974, Jarama

We also rather like Lauda's compatriot Alex Wurz's birthday salute: "Happy birthday Niki Lauda! One day please come to a @GPDA_ meeting and tell us drivers how you pulled off the driver strike back in the day."

11:20 Bottas continues round on hard tyres with the track to himself, lapping in 1m30.5s now. Sainz is coming out again too.

11:22 Rosberg is also coming back out in the Mercedes.

11:23 Lap count latest:

Rosberg 58
Sainz 54
Vettel 52
Bottas 46
Grosjean 40
Kvyat 33
Hulkenberg 30
Alonso 16
Nasr 3

11:23 Lap count by engine:

Mercedes 174
Renault 87
Ferrari 55
Honda 16

11:24 Sainz goes a little quicker again on another sprint run - he finds 0.08s and now leads with a 1m25.604s.

11:26 After setting his previous time-topping laps on softs, Sainz switched to super-softs for that one. Only a tiny gain, though.

11:26 Hulkenberg pops the Force India ahead of Rosberg's Mercedes into third with a 1m26.591s.

11:27 That was a brief soft-tyre run from Hulkenberg and he's now back in.

11:28 Vettel knocks a tenth off his best time, with a 1m26.312s that keeps him second but now 0.7s behind Sainz.

11:29 Kvyat, using mediums, finds a couple more tenths but stays eighth. Vettel is on softs once again for this run, and he drops 0.5s on lap two.

11:31 Back out on super-softs once again, Sainz falls 0.017s of his previous best.

11:31 On his third lap on softs, Vettel is now lapping in 1m27.2s, so his time dropped off by 0.5s from lap one to two, then another 0.4s.

11:32 Kvyat gains four tenths and pops ahead of Bottas and Alonso into sixth for Red Bull.

11:33 Alonso now improves, immediately grabbing sixth from Kvyat and getting within 0.037s of Grosjean in fifth.

11:35 Alonso improves to 1m27.956s, he's 2.3s off the pace but still on mediums.

11:35 We've got a red flag.

11:37 Cameras haven't found it yet, but seems to be Alonso's McLaren that's stopped.

11:38 Alonso completed his last lap so is somewhere in sector one... the computer locates him at Turn 4.

11:39 Still yet to get a look at the McLaren on screen, but lots of course cars can be seen heading through Turn 3 towards the scene.

11:40 Lap count while we're waiting:

Rosberg 68
Sainz 59
Vettel 59
Bottas 52
Grosjean 40
Kvyat 38
Hulkenberg 33
Alonso 20
Nasr 3

11:43 That's going to be Alonso's last outing for the week too, as it's only a quarter of an hour till the lunchbreak when he was due to hand over to Button anyway.

11:46 Of our top times today so far, Sainz's benchmark lap came on super-softs (but was less than a tenth faster than he did on softs), Vettel and Hulkenberg in second and third used softs, and the rest were set on mediums.

11:47 And if you're on a version of the site where you can't see results, here's a recap:

1 Sainz 1m25.604s
2 Vettel +0.708s
3 Hulkenberg +0.987s
4 Rosberg +1.178s
5 Alonso +2.352s
6 Grosjean +2.425s
7 Kvyat +2.545s
8 Bottas +2.567s
(no time for Nasr)

11:49 Lap count by engine:

Mercedes 193
Renault 97
Ferrari 62
Honda 20

11:50 The circuit's official feed reports that Alonso has crashed the McLaren. He's done so at a point out of camera sight.

11:53 It seems the McLaren went into the inside wall on the run between Turns 3 and 4.

11:53 The chequered flag has now been brought out for the lunch break as the session was due to pause in seven minutes anyway.

11:57 Although there is an ambulance at the crash scene, the circuit reports that Alonso is "OK and conscious".

McLaren12:02 This was the scene at McLaren as the crew waited for the car to be brought back.

12:03 The McLaren has now been recovered to the pits, pictured here from above as it arrived:

Fernando Alonso, McLaren, crash damage, Barcelona F1 testing, February 2015

12:06 The circuit data feed says Alonso lost control on the way out of Turn 3 and went across the track into the inside wall.

12:06 Alonso has been brought back to the medical centre in the ambulance.

12:07 "All the best Fernando," tweets Ferrari.

12:11 Here's our full report on the morning's action, a session that started with Nico Rosberg in the gravel and ended with Fernando Alonso in the wall:

REPORT: Alonso crash ends morning session early

12:12 Still waiting for further news from the circuit officials and McLaren-Honda, but the initial report on Alonso was he is "OK and conscious".

12:19 The circuit's medical helicopter has now taken off. Every indication is that Alonso requires precautionary checks.

12:21 From the circuit's official feed: "It seems that @alo_oficial is ok. We hope that everything's alright and all ends with just a shock!!"

12:23 Another angle of the McLaren being brought back to the pits. All the pictures so far suggest damage wasn't too dramatic:

Fernando Alonso, McLaren, crash damage, Barcelona F1 testing, February 2015

12:26 A large crowd had gathered around the medical centre as Alonso was brought back and then taken into the helicopter.

Fernando Alonso in medical helicopter, Barcelona F1 testing February 2015

12:35 An FIA spokesman at the medical centre has underlined that Alonso was conscious and talking, and has been transported to hospital.

12:45 More reassurance from Alonso's manager Luis Garcia Abad: "Fernando is OK and conscious. Thank you!"

12:46 Here's our most up-to-date story on Alonso:

Alonso taken to hospital after testing crash

12:55 Having safely delivered Alonso to the hospital, the medical helicopter is now back at the circuit.

12:56 Testing is set to resume on schedule at 2pm. We'll keep you informed about Alonso as we hear more from McLaren and his management.

12:58 A slight delay in the resumption of testing. The afternoon session will begin at 2.15pm.

13:09 As it's been an hour and a half and an Alonso-goes-to-hospital story since we informed you of the mileage completed today, here's a quick reminder before testing resumes:

Rosberg 68
Sainz 59
Vettel 59
Bottas 52
Grosjean 40
Kvyat 38
Hulkenberg 33
Alonso 20
Nasr 3

Lap count by engine:

Mercedes 193
Renault 97
Ferrari 62
Honda 20

13:10 And if you're on a version of the site where you can't see times, here they are:

1 Sainz 1m25.604s
2 Vettel +0.708s
3 Hulkenberg +0.987s
4 Rosberg +1.178s
5 Alonso +2.352s
6 Grosjean +2.425s
7 Kvyat +2.545s
8 Bottas +2.567s
(no time for Nasr)

13:13 Romain Grosjean's completing his first laps at Barcelona in the new Lotus today.

The Frenchman's media session took place during the lunch break, where he revealed Lotus will focus on "long runs and a little bit more set-up work" this afternoon.

It's been a much, much better introduction for the E23 than its predecessor.

Grosjean Barcelona Lotus

13:15 That's 2.15pm, and the session resumes. Some revving but no cars on track just yet.

13:16 We don't have to wait long at all though for that to change!

Rosberg leaves the Mercedes garage and the revving Red Bull below us also joins the track in Kvyat's hands.

13:16 Grosjean's quickly out in the Lotus, with the Williams of Bottas and Sainz's Toro Rosso out as well.

13:18 Rosberg and Sainz continue but Grosjean's back in.

13:19 Grosjean leaves the pits again and Lotus confirms that it's a long run.

"Come on @RGrosjean, it must be time for an afternoon race simulation? Let's see what you've got."

13:24 Bottas and Grosjean are both on soft tyres and lapping in the 1m30s.

That's the same bracket as Kvyat (on winter hards) and Sainz (not sure on tyres but will run to the window next time).

13:25 A series of laps in the 1m29s for the medium-tyred Rosberg.

Sainz, by the way, is on softs.

13:27 Rosberg's in, but then heads back out pretty swiftly.

Sainz also pits in the Toro Rosso.

13:29 We've got Vettel on track now in the Ferrari. Nasr finally emerges in the Sauber as well.

13:29 Rosberg back in again in the Mercedes.

13:29 Bottas and Grosjean lapping very similarly , thought the Lotus has dropped off the last couple of laps.

13:30 Nasr successfully completes the trip round the circuit in the Sauber and is back in the pits again.

Rosberg rejoined immediately in the Merc.

13:31 Grosjean's laptimes jumped to the 1m33s but have been consistent since. Bottas is creeping up, his last lap was a 1m32.0s.

13:32 Looks like there is swiftly a theme developing at Mercedes as Rosberg comes in and goes out again, for the third time.

Kvyat's back in now in the Red Bull. Engine's off as well.

13:34 Vettel, Rosberg, Grosjean and Bottas remain on track.

Grosjean's times have fallen away properly now, that last lap was a 1m36s. Rosberg completes his latest drive-through.

13:36 Grosjean pits now, and takes on mediums. Vettel's lapping in the 1m30s in the Ferrari. Bottas continues in the 1m32s.

Looks as though Rosberg's last visit to the pits ended with him in the garage.

13:38 Vettel pits in the Ferrari.

Grosjean is immediately into the 1m31s on his mediums. Bottas has managed his soft tyres for 13 laps and counting.

13:38 Sainz and Nasr are on track now.

13:41 The Toro Rosso and Sauber are both on softs.

Nasr uses his to set his first timed lap of the day, a 1m31.906s.

13:44 NASCAR driver Jeff Burton and IndyCar driver Graham Rahal may not be following AUTOSPORT Live, but they are aware of what's going on at Barcelona.

@JeffBurton: "Hoping Alonso is ok."

@GrahamRahal: "Hoping @alo_oficial is ok, he’s the man. Tough go for McLaren to start this year off."

13:45 Bottas pits after a 16-lap stint on soft tyres. His laptimes on lap 14 were what Grosjean fell to on lap seven. Fine work from the Williams.

13:45 Nasr has jumped to fifth on his soft tyres. The Sauber's best is now a 1m27.366s.

13:47 Bottas took on mediums in the pitstop. He's come straight back in though – and the car didn't sound great in the pitlane.

We'll let you know if it's a problem or planned stop.

13:48 Williams' Twitter account says this was supposed to be a race simulation for Bottas and we don't know too many grands prix that last 17 laps. He's not continued after pitting.

13:51 Just Sainz, Nasr and Grosjean left on the track.

Their respective last laps were: Sainz, 1m30.4s; Nasr, 1m28.804s; Grosjean, 1m31.124s.

13:52 Sainz brings his Toro Rosso back into the pits. It's switched off and that's his time on track done for a while.

13:52 And not long after that, Nasr comes into the pitlane as well. The Sauber's up to 13 laps completed for the day.

13:53 Nasr's popped out the other side of the pitlane now, and Vettel's returned to the track in the Ferrari.

13:55 Vettel's back in the pits, then out the other side again.

Nasr's also back in, but from the noise we can hear, seems as though he's continued as well.

13:56 Grosjean didn't pit but his last lap was 2m15s. A very slow middle sector.

13:59 The next two laps after that are better from Grosjean. Vettel's first flier of this run is a 1m30.1s and Kvyat's left the garage.

Nasr continues to flirt with the pitlane.

14:00 Quick lap from Kvyat. Two personal bests in the first two sectors.

14:01 Kvyat jumps to fifth in the Red Bull. The Russian improves his best to a 1m26.935s.

14:03 A cool-down lap from Kvyat, but now he's pushing again. He sets a personal best first sector and his middle sector is decent as well.

14:04 Looks like Kvyat's just matched his laptime to the thousandth. Impressive!

Daniil Kvyat, F1 testing 2015

14:06 McLaren has issued this statement regarding Alonso's accident and treatment:

"Today at 12:35 CET, while testing at the Circuit de Catalunya (Barcelona), during the fourth and final day of the current test, Fernando Alonso's McLaren-Honda car left the track at Turn Three, causing the right-hand side of his car to strike the wall.

"Fernando was driven to the circuit's medical centre where the circuit's doctors gave him first aid.

"He was conscious and spoke with the doctors.

"However, as per usual procedure in such circumstances, he was then airlifted to hospital where he is undergoing precautionary checks.

"We will issue a further update in due course."

14:07 Grosjean pits and briefly we're without any cars on track. But the Lotus rejoins swiftly enough to continue with his race run.

14:07 And now Bottas comes out as well. We're looking into whether that was an enforced delay or part of the plan.

14:09 Bottas is out on hards in the Williams. When he stopped, he'd just taken on a set of mediums. MATT BEER's off to the roof to see what clues he can spy on the Williams pitwall.

14:11 BEN ANDERSON's digging has come up trumps. Williams claims it was a planned stoppage for Bottas - a soft-tyre run and interim lap on different tyres before a delay, then a run on the hard-compound Pirellis.

14:12 Nasr leaves the pits in the Sauber.

14:14 Grosjean's on the mediums. His and Bottas' laptimes last time round were 0.010s apart - in favour of the Williams.

14:15 Nasr uses the soft tyres to jump to second in the Sauber, 0.517s behind Sainz's morning benchmark on a 1m26.121s.

14:18 Consistent 1m30s for the Lotus and Williams. We don't know fuel loads of course, but it's an impressive pace on the hard tyre by Bottas.

14:19 Hulkenberg went out in the Force India, but it was only a brief appearance.

Nasr's latest effort to improve ends in a 1m26.6s. Not quite.

14:23 Nasr's into the 1m27s now as Kvyat jumps to third on a 1m26.179s. We'll grab his tyre information next time through.

14:25 Nasr ends his run on the softs and is pushed back into the pits.

Kvyat's last lap was a cool-down attempt and we forgot to run to the window because BEN ANDERSON was busy bring us cups of water. What a doll.

14:26 And now we know – Kvyat's on mediums. Given Sainz's best effort came on the super-soft tyre, which should have a 1.5s-2s advantage, that's very good.

14:26 Red flag. It's Hulkenberg.

14:27 The smokey Force India has stopped at Turn 1.

14:27 That came just after this tweet from Force India:

"Nico completed his instal lap following some lunchtime checks and changes and is now heading out for his first run proper."

14:28 Hulkenberg pulled off on the run-off at Turns 1/2. Here's what we can see on the CCTV:

Nico Hulkenberg

14:29 Smoke is definitely still emanating from the Force India. Would it be harsh to suggest this doesn't really matter given it's the old car, and really the frustrated people here will be the other teams who have brought a relevant chassis and engine with them?

14:33 The Force India is still smoking. It's very substantial.

We're debating with a Spanish colleague whether or not it has completely fried itself on the inside. Whatever it is, it isn't pretty.

14:34 It looks like the Force India's Mercedes engine has expired in dramatic fashion and dropped a heap of fluid down to Turn 1.

We don't know that for certain but a very quick pan of the CCTV camera on the screens in the media centre made it look like there was something odd on the racing line and then leading to Hulkenberg's stricken car.

14:35 Speaking of the car, its now been covered up, but we can still see smoke coming out from under the sheet. Despite that, the rescue crew are loading it onto the back of the flatbed truck.

14:38 Earlier we asked you what your favourite F1 race ever was. It wasn't a competitive 'vote', but if it had been, the verdict would have been Canada 2011 by a mile!

That was the race in which Jenson Button famously charged from last to first to claim a dramatic victory, cracking Sebastian Vettel and causing the champion to spin on the final lap.

It was a sensational race, in which Button made contact with Fernando Alonso's Ferrari and then-McLaren team-mate Lewis Hamilton.

Here's what some of you had to say:

@Lewis44_Hulk27: "The 2011 Canadian Grand Prix!!! #AutosportF1 @autosport @autosportlive"

@lloydeh_B: "#autosportF1 has got to be that race where we saw vettel crack and button take that amazing win..."

@Sam_427: "China 2012, the battle for second was intense. I'm sure Canada 2011 is up there also. #AutosportF1 @autosportlive"

@DGrabko: "@autosport #autosportF1 2011 Canadian GP Button's amazing victory passing Vettel on the last lap."

@matbetteridge: "@autosport Canada 2011 by a mile, variable weather, safety cars, crashes, great overtakes, amazing Button performance and 4 hours long!"

@Stuart_Rowland: "@autosport Canada 2011. 6 pitstops. Plumb last with 20 laps to go. Takes the lead on [final] lap. Do races get any better? #autosportF1"

Jenson Button, Canadian GP 2011

14:39 The Force India is being brought back to the pits now.

14:41 We're green again so there can't be too much wrong with the run down to Turn 1 after all.

Sainz and Rosberg are swiftly out.

14:42 Hopefully for BEN ANDERSON this means he'll be able to enjoy some trackside action. He'd just headed out before the Force India stopped.

His response: "Just my luck!"

14:43 We've got Bottas back out in the Williams as well.

14:45 Grosjean rejoins in the Lotus now, so we have at least two cars on track who had previously been working on some long runs.

Kvyat's also on track.

14:47 Bottas is on hards. In other news, the grandstand is slightly more populated than it was when the afternoon session started.

Alonso's departure after his crash prompted an exodus of fans.

14:48 Good lap on the cards for Kvyat - great lap actually.

The young Russian goes top on a 1m24.941s.

You have to assume that's on the soft tyre. We'll confirm next time round.

14:51 That was indeed a soft-tyre run from Kvyat. Effective.

We've got three cars on track: Bottas (constant 1m30s); Rosberg (1m27s) and Sainz (1m31s).

14:52 Nasr is back out again as Sauber tries to make up for lost time.

14:54 Another improvement straight away from Nasr, who goes second, 0.546s down on Kvyat.

14:56 Grosjean's now the one looking to improve, as he sets a personal-best first sector in the Lotus.

14:57 Grosjean, on the softs, leaps to third, just 0.007s slower than the Sauber.

14:58 Grosjean's going even quicker on this lap, his first sector's purple.

Slightly busier track now as Kvyat rejoins having stopped, and he sets a personal-best first sector.

14:58 Grosjean doesn't carry that through to the end of the lap, and he falls a tenth short of his best.

Romain Grosjean, F1 testing 2015

14:58 Red flag.

14:59 There's an emergency vehicle shooting through Turn 3.

Could be Nasr.

15:00 It's not Nasr, it's Sainz. He was a long run.

The Toro Rosso is stopped at Turn 3 just out of sight of our CCTV at Turn 2.

That's where Alonso went off earlier.

15:01 So, we've got less than two hours to go, and this stoppage seems a perfect time to bring you up to speed on what's happened so far...

15:03 Looks like Sainz has lost it on the outside of Turn 3 and spun into the gravel. Seem the Toro Rosso has ended up in the tyre barrier.

15:04 It looked very much that way and now Force India confirms Hulkenberg's recent problem was an engine failure:

"Nico's car has been stopped by a power unit issue which we will investigate back at the factory."

So that's Force India's week done.

15:07 Headlines of the afternoon session with two hours to go:

* Kvyat uses soft tyres to go quickest on a 1m24.941s

* Nasr and Grosjean also improve on the soft and run second and third

* No sign of McLaren-Honda, with Button yet to take over driving duties following Alonso's crash that led to the Spaniard being airlifted to hospital

* Hulkenberg causes the afternoon session's first red flag when the Force India suffers a power unit failure

* Sainz's off causes another stoppage

* Rosberg (95) and Bottas (94) lead the lap count

15:08 News from McLaren, reports BEN ANDERSON: "Alonso has had CT scan. No injuries says the team.

Anderson adds: "Button's not expected to be out today. It's not looking likely."

15:12 Green flag. Running resumes.

Laps completed so far:

Rosberg 95
Bottas 94
Sainz 88
Grosjean 88
Vettel 69
Kvyat 63
Hulkenberg 36
Nasr 30
Alonso 20

15:14 Kvyat, Grosjean and Bottas are the first returnees to the track after the latest stoppage.

15:15 Confirmation from McLaren that Button will not run today and that's it for its running:

"That’s the end of our programme here at the first Barcelona test. Thank you for all your messages of support for Fernando."

15:17 Meanwhile there's been another red flag almost immediately. Looks like Bottas.

15:18 Bottas was the last car to be registered on the timing system as out on the circuit, but according to the computer they're all back now...

15:20 The computer system now picks up Bottas as the red flag cause, saying his Williams is stopped at Turn 4.

15:23 This was Sainz's Toro Rosso returning to the pits after his crash at Turn 3 a few minutes ago.

It was hard to tell the extent of damage under the sheet, bar when the wind blew the cover off the front a little and revealed some nose mangling...

Carlos Sainz Jr

...but the amount of bodywork, looking like both front and rear wing components, being unloaded from the pick-up truck that followed the car in was pretty revealing.

Carlos Sainz Jr

Sainz had a quick trip to the medical centre it seems but hopped out of the course car under his own steam and seems fine.

15:28 Green flag. Let's try again. An hour and a half to go.

15:29 Here's the latest on Fernando Alonso's health and the early exit for McLaren-Honda:

Fernando Alonso uninjured in F1 testing crash, McLaren packs up

15:29 Kvyat, Nasr, Grosjean and Rosberg are all out to try and rack up some mileage.

15:31 Grosjean flies to top spot on soft tyres with a 1m24.681s.

15:32 With Sainz and Alonso shunting and Hulkenberg and Bottas breaking down, we're a little short of cars as the Barcelona test nears its end.

15:32 Personal best for Nasr, but he misses out on pipping Kvyat to second for 0.015s.

15:34 To do that time, Nasr's on the super-soft Pirellis.

Great lap from Grosjean, only 0.3s shy of where Maldonado was yesterday on the red-walled Pirellis.

15:35 Nasr tries again and does a personal-best first sector but ends up half a second back from his best effort from before.

15:37 Job done, Grosjean returns to the pits. Kvyat and Rosberg remain on track.

15:41 We were up on the roof to watch Bottas's Williams being brought back after stopping on track to cause the last red flag.

No truck of debris trailing this one in, just a mechanical failure.

And Bottas was back on the pitwall having a cup of tea (maybe?) long before the car reappeared.

Valtteri Bottas

15:42 We were just about to say Sauber would want to see a bit more from Nasr on the super-soft tyre than being 0.2s slower than a soft-shod car.

He's gone purple in sector one.

15:43 Hmm...Nasr's lap is very slow in the end. He came out of the last corner just ahead of Kvyat. Did he catch him at the chicane?

In any case, he slows on the main straight and lets the Red Bull go by.

15:44 Rosberg has surged past the 100-lap mark. The German's on his 107th lap of the day. Mercedes not showing its hand. It doesn't need to. We saw how strong it looked on Friday.

15:46 Nasr goes for it again after backing off to let Kvyat past, and it's a good effort - but 1m25.1s is all it is.

15:46 Grosjean's set the fastest first sector of anyone so far. Lotus is reborn in 2015. Maybe a bit bold to say that about the E23 at this stage...but it looks a great deal better than the E22!

15:47 And on the super-soft Pirellis, Grosjean sets the best time of the week so far – 1m24.067s.

15:48 Bottas returns to the track in the Williams. We'd expect an improvement if it was anyone else, but this team has been a pain to read all week.

15:50 Very, very minor improvement from Bottas. He takes 0.007s off his previous best.

15:53 It's just Bottas (on hards) on track at the moment, but BEN ANDERSON has been watching the recent runners trackside at Turn 10. Grosjean doesn't "seem bothered with making a classic apex at the hairpin, preferring to carry more momentum in and make the turn later".

He also spies "a group of three Ferrari personnel gathered at the hairpin to take pictures of the cars, can't beat a bit of pre-season reconnaissance!"

15:54 Rosberg and Grosjean rejoin the track and Bottas is no longer on his own.

15:55 Another one of those "go fastest simulations" for Lotus. Grosjean's purple in sector two but doesn't improve overall!

The team joked before that run that he needed to try harder. We agree. We want to see a 1m23s effort before the end of the day.

15:57 A change in the order of the Nicos. Rosberg passes Hulkenberg on the leaderboard with a time of 1m26.506s.

15:58 Rosberg makes another slight improvement, and is now on a 1m26.414s.

15:59 Grosjean's back in after his last attempt to go fastest...failed? He's still fastest. So it's kind of a success. But he didn't go faster. Such things are moot, in all honesty.

Back to Rosberg and Bottas we reckon...

16:00 We can hear an engine fire up. Be it Kvyat's Red Bull, or Sainz's Toro Rosso?

We suspect it is the Red Bull.

16:01 It is the Red Bull. Kvyat rejoins the fray. Rosberg fails to improve on that run.

Winding down now, just under an hour to go. It's been a busy week. If anyone fancies bringing AUTOSPORT Live a Twix in celebration, feel free. Just above the Red Bull garage. Purple shirt, white Macbook. Thanks.

16:02 Nasr rejoins in the Sauber.

16:03 Rosberg pits. He was on the winter hards.

16:06 Whistles from the remaining spectators (the crowd diminished once Alonso was sidelined) as Vettel appears at the front of the Ferrari garage. We couldn't quite see if he answered their requests for a wave back.

16:07 Here is where we stand with less than an hour remaining:

* Grosjean leads by almost 0.9s with the fastest time of the test, set on super-soft tyres

* Alonso crashes at Turn 3 but escapes injury, although McLaren-Honda is forced to end its test early

* Sainz shunts on the outside of the same corner

* Bottas causes a red flag but rejoins in his Williams, which has logged 108 laps

* Rosberg remains the busiest driver on 114

16:08 1m29s laps for our three on-track runners – Kvyat; Nasr; Bottas.

Bottas is nearing Rosberg's day-best tally with every passing lap.

16:09 We've spent some of this afternoon on the roof on 'pitboard watch' with Bottas and Grosjean ostensibly on race simulations - though the red flags skewed things rather, with Grosjean binning the race after two stints and going into qualifying mode instead, and Bottas interrupted when he stopped on track.

At the start of the session, the Lotus pitboard was counting down from L65 while the Williams version was counting up. But the latter has switched along the way and is now counting down in what looks like the final stint of a drawn-out two-stop softs/hards/hards race to us.

16:09 Nasr's back out and on hards. Apologies, we believed Sauber's tweet, which confused the red-walled super-softs with the orange-walled hards.

16:11 Rosberg's rejoined. Clearly Mercedes doesn't want to relinquish the title of 'Sunday's busiest team'.

16:12 Good first sector for Rosberg, a personal best. Is this a late rise up the leaderboard on mediums?

16:14 That is seriously quick from Rosberg. He goes second on a 1m24.584s, and he is indeed on mediums.

Nico Rosberg, F1 testing 2015

16:19 Whenever Rosberg or Vettel has done something great, Michael Schmidt of AMuS yells "Heikki!", which we assume is to get the attention of Finnish journalist Heikki Kulta and point out how they have done a better job than Raikkonen.

It's almost as if there's an ongoing rivalry. There are plenty of esteemed people in our vicinity. And they have very good banter. It's been a test highlight.

16:21 Back to the track. No change since that stunning lap from Rosberg, who has now pitted.

Nasr and Bottas are the only two that remain on track.

16:22 Just to quantify how good that Rosberg lap is - Pirelli says the super-soft is 1.5s-2s quicker than the medium. So a 1m22.5s, really...

16:27 We've got Grosjean back on track, just as Bottas pits having beaten Rosberg's lap tally. Can you see this, Mercedes? Send him back out.

16:30 This has been a good run from Nasr in the Sauber, who is about to complete his 60th lap. Not a bad return after how it started.

Grosjean's back in.

16:32 Grosjean's back out in the Lotus again. The Red Bull's been fired up below us and Kvyat pulls out of the garage on medium tyres.

16:35 Rosberg's back out, and so is Bottas.

16:36 Good lap from Bottas, two personal bests in the first two sectors.

He's on soft tyres, and carries his performance through to the end – improving to fifth on a 1m25.345s.

16:38 Rosberg's gone even quicker.

He sets a personal-best middle sector and then is purple in the final third of the lap.

He stays second but his laptime is now 1m24.321s. If that's on the mediums, it's effectively 1.8s faster than Grosjean's Lotus on super-softs.

16:38 It is on mediums. Mercedes is flexing its muscles here.

16:40 Bottas goes again after a cool-down lap but it's only a 1m26.2s. Williams hasn't shown its hand so far and we'd be very surprised if it's 1s slower on softs than the Mercedes is on mediums.

16:42 It's been 2h40m since we saw Vettel on track. The Ferrari's only logged 69 laps today. It's not set a bad time on the mediums. Well, when you compare it to anything other than the Mercedes anyway.

But you'd have thought it might do something else today. Just over 15 minutes remaining for it to do so.

16:44 And speak of the devil...Vettel joins the track.

16:51 Red flag. The Sauber is stopped at Turn 6.

16:51 That could be the end of the day.

16:51 Apologies for the lack of updates before then – Nasr in the 1m29s and Vettel, on hards, in the 1m30s was all that was happening.

16:53 Here's the stranded Sauber among a gaggle of recovery vehicles on the way into Turn 6.

Felipe Nasr, Sauber, Barcelona F1 testing, February 2015

It's been a tough few days for that team reliability-wise.

16:56 One of our other red flags this afternoon came from Sainz crashing the Toro Rosso at Turn 3.

Here's team boss Franz Tost's verdict on it:

"We are still going through the data to understand the cause, so it’s a bit early to conclude; however, it is fair to say that the winds have been extremely high and gusting today, and we have seen a few other cars have offs as well."

16:57 Unlikely to be much/any more running with three minutes on the clock, so here's a lap count:

Rosberg 129
Bottas 127
Grosjean 111
Kvyat 102
Sainz 88
Vettel 74
Nasr 73
Hulkenberg 36
Alonso 20

16:59 A green flag with less than a minute remaining. Interesting.

17:01 Chequered flag. The second pre-season Formula 1 test comes to an end.

17:11 That's it for our four days of coverage from Barcelona. You won't have to wait long for more testing as the teams are back in action on Thursday, and until then we'll have plenty of coverage and analysis to keep you occupied over the next few days.

For now, we'll sign off by leaving you with our report from the final day of action, as Mercedes gave everybody something to think about:

REPORT: Grosjean fastest but Mercedes catches the eye

We'll see you again just before 8am on Thursday for coverage from the final pre-season test before everyone heads to Australia for the first GP of the season.

P Driver Team Time
1  Romain GrosjeanLotus 1m24.067s
2  Nico RosbergMercedes 1m24.321s  +0.254
3  Daniil KvyatRed Bull 1m24.941s  +0.874
4  Felipe NasrSauber 1m24.956s  +0.889
5  Valtteri BottasWilliams 1m25.345s  +1.278
6  Carlos Sainz JrToro Rosso 1m25.604s  +1.537
7  Sebastian VettelFerrari 1m26.312s  +2.245
8  Nico HulkenbergForce India 1m26.591s  +2.524
9  Fernando AlonsoMcLaren 1m27.956s  +3.889
All timing unofficial. Updated: 16:38 GMT
Clear skies High Temp: 12°C / 54°F
Track: Dry
Loading info ...