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As it happened: Test day one
By Glenn Freeman, Ben Anderson, AUTOSPORT staff, Lawrence Barretto and Mitchell Adam
The live commentary has ended. No further updates will be posted.
07:51 Good morning (or indeed afternoon or evening wherever you are in the world) and welcome to AUTOSPORT's Live coverage of the third and final pre-season test.

07:53 We're set up in the Barcelona media centre and ready to bring you the action over the next four crucial days.

07:54 Joining you from a mild but clear circuit this morning we have Ben Anderson, Lawrence Barretto and Mitchell Adam.

07:56 The new Force India will not hit the track until tomorrow, which means we'll have just eight drivers in action today:

Mercedes - Hamilton
Red Bull - Kvyat
Williams - Massa
Ferrari - Raikkonen
McLaren - Button
Toro Rosso - Sainz
Lotus - Grosjean
Sauber - Ericsson

07:58 If you missed the news yesterday, here's the full story on Force India's new car, to get you up to speed before the session goes green in a couple of minutes.

07:59 The other big news is that Fernando Alonso won't get behind the wheel this week, following his accident on Sunday. He left hospital yesterday, Kevin Magnussen will replace him behind the wheel at McLaren this week.

08:00 BEN ANDERSON: "After the 'shadow boxing' of last week's test, this should be the one that reveals most about where the teams actually stand relative to one another before heading to Melbourne.

"Ferrari is finally planning to do some race simulations at this test, having previously focused on reliability, systems checks and set-up work. This will give us clearer indication of whether the Scuderia has really made the progress it appears to have done over the winter.

"Likewise, Renault will bring a number of hardware and software updates to this test, and we should see the Red Bull and Toro Rosso running at full power finally.

"The Mercedes-powered teams all sound confident, and well they might given the reliability and pace they've shown so far in pre-season.

"The same cannot be said for McLaren-Honda, which suffered badly from a recurring ERS problem at the last test, compounded by the crash that has sidelined Fernando Alonso from driving this week. The Woking team is well behind schedule in its Melbourne preparations."

08:01 And we're go. Raikkonen and Ericsson are the first to take to the track, followed by Massa.

08:03 Ericsson and Massa have continued, Raikkonen has returned to the pits after completing his installation lap.

08:04 Carlos Sainz Jr, the sole Spaniard in action this week, has now left the pits in the Toro Rosso.

08:06 Ericsson and Massa return to the pits, Hamilton goes the other way, leaving pitlane in the Mercedes.

08:09 It's a lovely clear morning in Barcelona, though there's a chill in the air. The air temperature is a 5.4C and track temperature just 8.9C.

08:11 We're only a few minutes into the session and we've already got our first red flag of the day.

08:13 It's Red Bull's Daniil Kvyat. The Russian has stopped at the end of the pitlane.

08:13 A rumble beneath the media centre was a sure sign Red Bull was getting ready for action. Kvyat headed out briefly in the Camo machine - not that it got too far.

Kvyat, Red Bull, testing

08:15 We're back to green as the Red Bull boys did a speedy job running down to the pit exit to recover Kvyat's car before pushing it back to the garage.

08:18 Raikkonen's wasted no time following the restart, he's just blasted past the media centre to start what could be the first timed lap.

08:19 And there it is, a 1m32.451s. Kimi continues.

08:22 Raikkonen improves to a 1m30.703s. He's joined on track by the Red Bull, obviously nothing too serious with the earlier stoppage.

08:24 Kvyat returns to the pits, Raikkonen has the track to himself again. Other than McLaren and Lotus, everyone has been out.

08:26 Kimi improves again, to a 1m30.271s, as Sainz rejoins the fray.

08:29 A pair of world champions trade places. Raikkonen pits, Jenson Button leaves pitlane.

08:29 He's now back on track and running already, but this was the scene just a few minutes ago as Kvyat's Red Bull was being retrieved.

Pleased to see the same pitlane marshal team in action as last week. When cars are being retrieved, they stand at the relevant garage holding flags aloft so the truck crew know where to bring the broken car.

Last week one of them made herself more visible still by having a light knee-based mini-dance to the pounding R&B/europop being played through the grandstand speakers during lulls.

Daniil Kvyat, Red Bull, breaks down, Barcelona F1 testing, February 2015

08:31 Button has completed his installation lap. It's a big week for the renewed McLaren-Honda partnership after troubled times at Jerez and here last week.

BEN ANDERSON reports McLaren has been helping the Japanese manufacturer with its MGU-K system.

08:33 First timed laps for Massa and Hamilton, who currently share the track. Massa has logged a 1m27.105s, Hamilton a 1m31.669s.

08:35 Massa, on the hard compound Pirelli, improves to a 1m26.867s.

08:36 On hards, Hamilton also improves, to a 1m26.787s. Teams are getting straight down to business.

08:40 Hamilton is putting a bit of a stint together, improving to a 1m26.437s

08:42 With home favourite Fernando Alonso skipping this test to continue his recovery following his crash here last week, it's not a surprise to see the grandstands are sparsely populated this morning...

There's only around 20-odd people in the main stand that straddles the start-finish straight - but they've all come prepared for the early morning chill with thick jackets, beanie hats and gloves.

Though this bold bunch of Merc fans have shunned gloves to allow better waving.

Lewis Hamilton fans in Barcelona F1 testing, February 2015

08:48 For what it's worth, here's the list of fastest times we saw at Barcelona several days ago, complete with tyre details.

1. Romain Grosjean Lotus-Mercedes 1m24.067s (SS)
2. Nico Rosberg Mercedes 1m24.321s +0.254s (M)
3. Pastor Maldonado Lotus-Mercedes 1m24.348s +0.281s (SS)
4. Daniel Ricciardo Red Bull-Renault 1m24.574s +0.507s (S)
5. Kimi Raikkonen Ferrari 1m24.584s +0.517s (S)
6. Felipe Massa Williams-Mercedes 1m24.672s +0.605s (S)
7. Sergio Perez Force India-Mercedes 1m24.702s +0.635s (SS)
8. Max Verstappen Toro Rosso-Renault 1m24.739s +0.672s (SS)
9. Lewis Hamilton Mercedes 1m24.923s +0.856s (M)
10. Daniil Kvyat Red Bull-Renault 1m24.941s +0.874s (S)
11. Felipe Nasr Sauber-Ferrari 1m24.956s +0.889s (SS)
12. Valtteri Bottas Williams-Mercedes 1m25.345s +1.278s (S)
13. Carlos Sainz Jr Toro Rosso-Renault 1m25.604s +1.537s (SS)
14. Fernando Alonso McLaren-Honda 1m25.961s +1.894s (S)
15. Jolyon Palmer Lotus-Mercedes 1m26.280s +2.213s (S)
16. Sebastian Vettel Ferrari 1m26.312s +2.245s (S)
17. Marcus Ericsson Sauber-Ferrari 1m26.340s +2.273s (S)
18. Nico Hulkenberg Force India-Mercedes 1m26.591s +2.524s (S)
19. Pascal Wehrlein Force India-Mercedes 1m27.333s +3.266s (M)
20. Jenson Button McLaren-Honda 1m28.182s +4.115s (M)
21. Pascal Wehrlein Mercedes 1m28.489s +4.422s (H)
22. Susie Wolff Williams-Mercedes 1m28.906s +4.839s (M)

08:49 While you peruse that over the final stretch of your commute to work, Kvyat has just left pitlane again in the Red Bull.

08:51 Button, meanwhile, has been out to complete a second installation lap.

08:53 Grosjean has also completed an installation lap. We've seen all eight cars inside the first hour.

08:55 Speaking of laps, Kvyat has completed his first timed tours of the circuit. The second is a 1m28.465s

As we approach the end of the first hour, here's a look at how busy each driver has been.
Hamilton - 9
Massa - 9
Kvyat - 6
Raikkonen - 9
Sainz - 6
Ericsson - 5
Button - 2
Grosjean - 1

08:58 At this stage many teams are focusing on aero data logging - some using large sensor contraptions (we've seen a particularly big one on the Toro Rosso already), and others using flow-vis paint, like this colourful Sauber:

Marcus Ericsson, Sauber, Barceona F1 February 2015

08:58 Next time around, Kvyat improves to a 1m27.825 to go third fastest, 0.958 seconds off the pace. He's joined by the Sauber of Marcus Ericsson.

Meanwhile, down on the inside of Turn 1, a chap has just strolled over and pitched up on a wooden plank, the best of the seating options down that way, and has a perfect view as the cars power through Turn 2.

He's nibbling on a packet of crisps, though I can't see what brand...

09:02 It's all going rather well for Hamilton at the moment as he improves on his quickest time with a 1m25.976s. That's 11 laps ticked off.

09:04 Hamilton, rocking the medium tyres, goes quicker still with a 1m24.881s, 1.986s clear of the field. Ouch.

09:07 Hamilton is continuing his run. No improvement on his last two laps, but you'd hardly call a 1m25.750s and 1m25.533s tardy on the mediums.

Lewis Hamilton, Mercedes, Barcelona F1 testing February 2015

09:08 And, just as that is typed, he pits. Not so much a commentator's curse as a commentator's 'IN' pitboard...

09:13 A lull in activity sees our crisp-loving friend from Turn 1/2 move on. We'll let you know if we spot him on CCTV again. Or if he moves onto other snacks.

09:14 Kvyat has broken the silence and headed back out.

09:15 Most teams will add significant upgrades for this test, and there's no hiding Toro Rosso's.

Its previous rounded nose design (on the right) has been replaced by a visually very different stumpy version:

Toro Rosso nose

09:15 ‏@ForceIndiaF1 Our VJM08 is currently on its way to Barcelona; we'll be aiming for action on Friday afternoon and on the two full final days. #FeelTheForce

09:16 Force India also confirms Hulkenberg will christen the new car on Friday afternoon and Saturday, with Perez getting behind the wheel on Sunday.

09:18 It's hotting up at the Circuit de Catalunya, so much so, a chap in the grandstand opposite the pitlane has ditched his jacket and jumper.

But with the air temperature having only crept up to 7.7C, with the track temperature up at 15.6C, rocking just a t-shirt is a bold move.

09:23 If you're just joining us, here's what you've missed on the opening morning so far:

* Lewis Hamilton sets the pace with a 1m24.881 on the medium tyres in the Mercedes.
* Daniil Kvyat causes the first red flag of the day when he stops at the pitlane exit.
* Carlos Sainz, Romain Grosjean and Jenson Button have yet to set a lap time.

09:26 Massa has returned to the circuit after almost three-quarters of an hour in the garage. Sainz and Grosjean - both yet to set a time - are keeping him company on track.

09:28 The Brazilian improves to a 1m26.399s, Grosjean logs his first time, a 1m28.625s.

09:32 Kimi Raikkonen heads out in the Ferrari and he's soon joined by McLaren's Jenson Button, who has been sat in the garage for the last 40 minutes or so.

09:34 And we have a time from the McLaren, with Jenson Button clocking a 1m31.479s. The Briton then heads back to the pits.

Jenson Button, McLaren, Barcelona, February 2015

09:37 You'll hear from KARUN CHANDHOK over the coming days, as part of AUTOSPORT's coverage of this test. The ex-F1 and current Formula E racer has been trackside, Turn 10 to be precise.

"Out on track, the Red Bull looks balanced, but none of them can get temperature in the tyres. That's the biggest issue, especially with the front tyres.

"Lewis is the only one who is forcing energy into the front tyres to get some temperature into them.

"The Toro Rosso has a strange, almost traction control-sounding system, like it's cutting cylinders for traction. But he's yet to do a laptime so maybe the tyres are cold."

09:39 As Karun notes, Sainz is still yet to set a laptime. And it is cold, air temp is 8.4C, track temp is 13.9C. Take your pick between 'fresh' and 'brisk'.

We'll bring you more of his observations over the next four days.

09:43 Kvyat moves the Red Bull up to second, the Russian clocking a 1m25.987s on the mediums. He pulls into the pits, stops in the box and is then pushed back into the garage by his mechanics.

09:44 Here's the latest lap count:

Kvyat - 21
Ericsson - 21
Hamilton - 18
Raikkonen - 18
Sainz - 16
Massa - 14
Grosjean - 13
Button - 5

09:52 Lewis Hamilton has been past the media centre, and the hearty souls in the grandstand, a few times in recent minutes. The world champion is onto his 25th lap of the day.

Hamilton, testing, Mercedes

09:53 Massa, Grosjean and Sainz - the latter still to set a time - are also on track.

09:55 Hamilton completes an eight-lap run on the medium tyres, lapping in the high 1m26s and low 1m27s throughout.

09:59 Grosjean has improved as we approach the end of the second hour of running. His best is now a 1m27.525s.

10:01 Two hours into the day, here's the full times, for those of you on a mobile device or the AUTOSPORT app.

1 Lewis Hamilton Mercedes 1m24.881s
2 Daniil Kvyat Red Bull 1m25.987s +1.106
3 Felipe Massa Williams 1m26.399s +1.518
4 Romain Grosjean Lotus 1m27.525s +2.644
5 Marcus Ericsson Sauber 1m29.172s +4.291
6 Kimi Raikkonen Ferrari 1m29.590s +4.709
7 Jenson Button McLaren 1m31.479s +6.598

Carlos Sainz has logged 21 laps, but is yet to record a time.

10:04 ‏@MercedesAMGF1 Two hours into the first day of the final test! 26 laps on the board for @LewisHamilton, 1:24.881 his best so far!

‏@MercedesAMGF1 To put that time into context, at the moment that's the second quickest time, whilst using medium tyres, of pre-season testing so far! #F1

@MercedesAMGF1 Second only to @nico_rosberg! #BackToWork #F1

10:05 Going by that triple tweet combo, Mercedes is fairly pleased with how things are progressing.

10:09 Button has completed another tour of the circuit and is now back in the McLaren garage. Hamilton, Kvyat, Grosjean and Ericsson are the men on track.

10:13 Hamilton is now the only man on track. He hasn't improved on his benchmark time this run (yet), but his 1m25.192s from the last lap is still almost a second faster than anyone else has gone.

10:14 The new restrictions on drivers changing their helmets design - revealed by AUTOSPORT last week - have ended up creating a bit of intrigue over the colours some of them are going to choose for the year ahead.

We're already getting used to Sebastian Vettel's German colours on white look, but has Grosjean got something new and artistic up his sleeve?

For the second week running he's sticking with this plain black look for testing.

Romain Grosjean, Lotus, Barcelona F1 testing February 2015

10:19 Hamilton is pushing on, on the medium rubber. Since posting his 1m25.192s, he's completed a 1m26.040s, 1m25.947s, 1m26.224s, 1m26.063s and 1m26.480s.

10:20 Massa, Ericsson and Raikkonen are now on track, ending Hamilton's private test.

10:21 Massa has improved to a 1m26.083s in the Williams, now within one one-hundredth of Kvyat.

10:27 Kvyat and Raikkonen are on track and have both marginally improved on their best times, to a 1m25.947s and 1m27.813s respectively.

10:27 Here's the latest lap counts:

Hamilton - 38
Ericsson - 33
Kvyat - 29
Massa - 24
Grosjean - 24
Sainz - 24
Raikkonen - 22
Button - 7

10:33 So, a quiet morning from McLaren-Honda, with seven single laps, as the renewed partnership continues to find its feet.

GARY ANDERSON analysed the progress so far, and declared there are 'no excuses'. Read his full take here.

10:36 "Okay @Max33Verstappen, enough spying..." tweets Toro Rosso.

"Let's get you something to do. A morning of interviews, for example? Deal!"

Verstappen has spent the morning so far out watching from trackside with dad Jos and some colleagues.

Max Verstappen

10:38 Max is now watching his team-mate Sainz conduct Toro Rosso's first meaningful run of the day after 25 installation laps. Accordingly, he's logged a time, a 1m27.866s.

10:39 On the medium tyre, Massa has moved up to second fastest, with a 1m25.763s.

10:45 Hamilton is back on track. Kvyat too, the latter's Renault sounding a little less like a tractor cruising down pitlane than Hamilton's Mercedes. Strange, no doubt limiter-induced sound.

10:47 No drama for Hamilton as he ticks into the 40s for laps completed today.

10:49 @MercedesAMGF1 Well this wasn't in the script. We think the technical term is 'proper drizzle' here at @Circuitcat_eng! #BackToWork #F1

10:52 Indeed, a quick trip to the roof confirms there is a very light drizzle falling.

10:52 The cloud cover had increased ever so slightly in the last hour or so, and has been followed by the current precipitation.

10:54 As a result, everyone is currently in pitlane.

10:58 Here are the top stories with just over one hour to go until the lunch break...

* Lewis Hamilton sets the pace with a 1m24.881 on the medium tyres in the Mercedes.
* Daniil Kvyat causes the first red flag of the day when he stops at the pitlane exit.
* McLaren's struggles continue as Jenson Button manages just seven laps, of which only one is timed.

11:00 This is about the extent of the rain. No umbrellas or raincoats in the grandstand as we wait for cars to return to the circuit.

11:02 During this unexpected lull, here are a couple of other F1 stories you might have missed yesterday.

Will Stevens has agreed a 2015 Formula 1 race deal with the returning Manor team, which expects to be ready to compete in the Australian Grand Prix. Click here to read the full story.

11:03 Formula 1's smaller outfits are pushing to be allowed to share more car parts in the future in a bid to help lower costs. Click here to read the full story.

11:14 There's still a bit of light drizzle around, so during this lull in proceedings, here's the latest lap count:

Hamilton - 42
Kvyat - 34
Sainz - 34
Grosjean - 33
Ericsson - 33
Massa - 29
Raikkonen - 28
Button - 7

11:17 And here's the latest times:

1 Lewis Hamilton Mercedes 1m24.881s
2 Felipe Massa Williams 1m25.763s +0.882
3 Daniil Kvyat Red Bull 1m25.947s +1.066
4 Romain Grosjean Lotus 1m27.079s +2.198
5 Marcus Ericsson Sauber 1m27.802s +2.921
6 Kimi Raikkonen Ferrari 1m27.813s +2.932
7 Carlos Sainz Jr Toro Rosso 1m27.866s +2.985
8 Jenson Button McLaren 1m31.479s +6.598

11:18 KARUN CHANDHOK has returned from the rain/drizzle/droplets to give us his thoughts on some of the cars he watched through Turns 7, 8 and 9.

“Turns 7 and 8 are good places to watch as the cars come though the dip. It’s nice to see a medium-speed corner and how the cars work through there.

“Grosjean kept locking the fronts, it looked like he was struggling to get brake balance right.

“When Sainz comes along, I don’t know if it’s conscious or not, but the way he turns the wheel reminds me of Fernando. He’s so aggressive. The car doesn’t look great, though, the rear end doesn’t look so stable, and traction and drive don’t look great either.

“I wandered up to Turn 9 as well, fast right-hander. The Mercedes looks like the perfect car. In Turns 7 and 9, it looks like it’s on rails. Lewis has so much confidence, he can do what he wants with it.

“Massa looked like he wasn’t trying, I think the car looks really easy to drive. The car didn’t move, it looked stable. I think Williams have a good base, to do have done that time [Massa’s 1m25.763s] on that run. It looked smooth to me, like watching Alain Prost!”

11:21 We hear an engine! Given its proximity, sounds like Kvyat is heading out.

11:25 We've already highlighted that Toro Rosso has a new nose for today's test, and the changes go far deeper than that.

Technical director James Key has been telling BEN ANDERSON that this is effectively a whole new car for the final test:

Toro Rosso reveals 'almost brand new' car

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

11:28 Kvyat is lapping on the intermediate compound Pirelli. No trails of spray behind him as he headed down the start-finish straight to start the fourth lap of this run.

11:30 There still is light rain falling, on the main straight at least.

11:34 Amid this drizzle and with the lunchbreak imminent, it's time to open up AUTOSPORT Live to you, the readers, for our midday social debate.

Today our question is: which circuit, or version of a circuit, would you most like to see back on the F1 calendar and why?

Tweet your answer with the hashtag #autosportf1 and we'll run through a selection of the best during the break.

11:35 Kvyat heads for the pits, perfectly hits his mark in the Red Bull box and is then wheeled back into the garage. The track falls silent.

11:39 Apologies to those of you who contributed to our last lunchtime discussion on the final day of test two - due to Fernando Alonso's accident and his transfer to hospital we didn't get a chance to share many of your suggestions.

Here's one that was popular - the 1987 British Grand Prix. It seems many of you were in attendance at Silverstone that day for Nigel Mansell's epic chase of Nelson Piquet:

Nelson Piquet, Nigel Mansell, 1987 British GP

11:39 It's not silent for long as Mercedes' Lewis Hamilton heads out to assess the track conditions...

11:44 The light drizzle has continued since our last 'rain watch' photo update. We're not Brick Tamland, or any other weather broadcaster for that matter, but it looks like it's going to stick around.

Barcelona, rain, testing

11:49 Kvyat and Hamilton have a slippery track to themselves at the minute on what has been a remarkably incident-free session. Just the one red flag so far and that came after just 10 minutes when Daniil Kvyat stopped his Red Bull at the exits of the pits.

11:53 Just Kvyat on track now, as we approach the lunchbreak. His last laptime on the damp surface was a 1m43.075s.

11:55 And now Kvyat returns to the pitlane. Likely to be the last running of the morning session, given the conditions and late stage.

12:02 And that's lunch!

12:03 Here's the full times from this morning, all set before rain arrived about an hour ago.

1 Lewis Hamilton (Mercedes) 1m24.881s
2 Felipe Massa (Williams) 1m25.763s +0.882s
3 Daniil Kvyat (Red Bull) 1m25.947s +1.066s
4 Romain Grosjean (Lotus) 1m27.079s +2.198s
5 Marcus Ericsson (Sauber) 1m27.802s +2.921s
6 Kimi Raikkonen (Ferrari) 1m27.813s +2.932s
7 Carlos Sainz Jr (Toro Rosso) 1m27.866s +2.985s
8 Jenson Button (McLaren) 1m31.479s +6.598s

12:04 Here's the lap count at lunch:

Hamilton - 48
Kvyat - 45
Sainz - 34
Grosjean - 33
Ericsson - 33
Massa - 29
Raikkonen - 28
Button - 7

12:06 Headline summary from the morning:

* Hamilton and Mercedes set commanding pace and top the lap tally
* Kvyat stops in pitlane to cause early red flag, but soon back out
* McLaren runs, but only for seven laps
* Rain shower means early end to most teams' running

12:15 Here's the full report and results from this morning so you can catch up with anything you've missed during lunchtime...

Hamilton tops Thursday morning at Barcelona

...And we'll be filling the gap with the best of your responses to the 'which circuit would you like to see back on the F1 calendar' Twitter question via #autosportf1.

12:21 Leading the way in your #autosportf1 suggestions for the circuit you want back on the F1 calendar is Imola, with huge enthusiasm for the old San Marino GP venue.

"Good and bad memories but a great track," says @F1lad, "it's a legendary track with always great races and a great history. I would take Imola over Monza," reckons @rebeldhipi and "Great circuit. Safety has improved massively since last F1 race there," says @R3DZ3.

Ralf Schumacher, Williams, San Marino GP 2003, Imola

12:24 With the new Force India set to arrive tomorrow, there's a farewell going on during the lunchtime pit walkabout.

"Pitlane open - a chance for the fans to come and say goodbye to the VJM07 as it nears its well-earned retirement."

12:31 Also a huge number of votes in the 'which circuit/circuit version would you like to see back in F1' for the longer Hockenehim layout.

@djhazardous nails it: "Those long straights through the woods were something else."

He's echoed by @the_real_simii ("such a challenge back in the day, long straights and not that wide! Exciting racing"), @BenIssatt ("future generations of F1 fans don't know what they missed!") and many more.

Mika Hakkinen, McLaren, German GP 1997, Hockenheim

12:33 Rewinding further into F1 history, here's an excellent choice from @willcampbell115:

"Mosport, even though it would only take about 45 seconds to do a lap."

The Canadian venue still hosts top-line sportscar racing but hasn't been used by F1 since the 1970s.

1972 Canadian GP, Mosport

12:36 If you're just joining us and are keen to catch up on the morning's testing action, here's the full report:

Hamilton fastest, more problems for McLaren

And we're keeping the lunchbreak ticking with your answers to this question: which circuit - or version of a circuit - would you most like to see back on the F1 calendar? Tweet your answers with #autosportf1.

12:40 Plenty of support from British fans and beyond for the Brands Hatch GP layout:

"Definitely want to see Brands Hatch return to the calendar! Proper classic circuit and a great test of ability!" says @TopherF1.

"So many iconic corners and great viewing for the fans. Never happen though unfortunately," adds @AdeMatthews.

"The run through the woods is both beautiful and terrifying in equal measure," is @Ryan_TWilliams' view.

Brands Hatch GP 1984

12:51 It's not just 'retro' circuits getting your votes in the 'which track do you want back in F1?' debate - there's a lot of love for Turkish GP venue Istanbul Park, which escapes the criticism other Tilke venues are getting.

@timmylegg: "Always great races, great undulation, Turn 8 and the cars side by side from Turn 10 to Turn 3"

@zacks1603: "Love that circuit (mainly because im a @MassaFelipe19 fan) but Turn 8 was a good challenge to the drivers"

@Gashead26: "Perfect combination of fast/slow,and gradient."

@ChrisBallard94: "Tilke's best track, wonderful to drive and see racing on."

And @Paul11MSport reckons: "If it wasn't in the middle of nowhere it would still be on the calendar "

Turkish GP 2007

12:54 We very much like how simple @HansenRacingDK makes this brilliant idea sound: "A real classic, that could be done, is the 14.1 km old Spa track. All the roads are still there,so just use them."

Belgian GP 1970, Spa

12:55 We've had surges of votes for Adelaide, Zandvoort, the original Osterreichring and Estoril as well, all fantastic choices.

12:57 The question was which track would you like to see back in F1, but first off the mark was @athlon29's request for a track that's never been on the F1 calendar but would be excellent:

"Laguna Seca with the amazing corkscrew chicane."

So we're going to include that too!

Max Papis, Rahal, Laguna Seca CART 2001

Thanks for all your responses, we'll be running a similar debate every lunchtime to the end of the test.

12:59 That almost brings us to the end of the lunch - 30 seconds until we get the green flag for the afternoon session.

13:00 The good news - especially for teams - is that the rain has stopped and the circuit should we well on its way to drying. A few cars running around should have it right in no time.

13:00 And we're off. Massa wastes no time, heading out in the Williams.

13:02 Ericsson has joined him on the circuit, the Sauber was fifth-fastest this morning.

13:03 Only for Massa to head straight back into the pits, bouncing on and off the limiter in a very deliberate manner. Actually looks like he's driven straight through the pits. Or completed a practice pitstop.

13:07 Massa, having completed his 'through the pits trick again' starts a lap using the start-finish straight this time. Ericsson has returned to the pits.

13:08 His first flyer is on the money, a 1m25.963s, just two-tenths shy of his morning best.

13:13 Massa is out on the soft compound tyre, most drivers having set their morning times on the medium. His 1m25s has been followed by a pair of 1m27s laps and now a 1m28s.

13:14 Raikkonen and Sainz are also currently on track. And for the first time in several hours, it looks sunny outside.

13:18 McLaren boss Ron Dennis spoke to the media not long ago about the latest on Fernando Alonso. Here's BEN ANDERSON's full story, explaining why there's still doubt surrounding the Spaniard returning in time for the Australian GP:

McLaren unsure on Alonso return date

Fernando Alonso, F1 testing 2015

13:21 Massa is into the ninth flying lap of his stint, the last five have been in the 1m30s. The other car on track, meanwhile, Sainz has improved to a 1m27.640s.

13:29 Sainz is running on the unmarked Pirelli tyres consistently in the 1m27s/28s bracket. Making up for a punctuated morning, he's up to 45 laps for the day.

13:31 Massa has been through the pits for another set of soft rubber. All signs point to a race sim for Williams. He'd be 15 laps in.

13:31 Ericsson is also circulating on the soft Pirelli tyres, while Kvyat has left the pits to make his afternoon debut.

13:32 That means it's just Hamilton, Grosjean and Button we're yet to see after lunch.

13:35 @LewisHamilton #InCarSelfie Have an amazing day today, #TeamLH!! Be GREAT!! #Love #BestTeam #GodBless

Lewis Hamilton Twitter selfie, F1 testing 2015

13:39 Fair selfie effort that from Lewis. Not sure whether he went for the 'flip camera to the front' mode or stuck with the traditional 'I think is where my head is while looking at the back of the screen' method.

Definitely doesn't look like a selfie stick effort, though.

13:41 We can also report that we're yet to see a selfie stick in the Barcelona grandstand. There's a reasonable turnout for an Alonso-less Wednesday and they've stuck with it through the earlier rain delay.

13:42 Good split of support, too. Through the media centre window, we can see flags for Raikkonen, Grosjean, Mercedes and a gentleman wearing a camouflage jacket - which we assume means he's supporting Red Bull's camo testing livery.

13:44 Speaking of Red Bull and Kimi, Kvyat and Raikkonen are both currently on track, along with Ericsson. Kvyat has become the second driver (after Massa) to crack a half-century of laps for the day. He's given the dressing room a quick wave of the bat and is pushing on with his stint.

13:48 Here's the full lap count for the day, with its new leader.

Kvyat - 54 (45 at lunch)
Massa - 52 (29)
Hamilton - 48 (48)
Sainz - 48 (34)
Ericsson - 48 (33)
Raikkonen - 34 (28)
Grosjean - 33 (33)
Button 7 (7)

Massa and Ericsson have been the busiest since lunch. Massa completed two 10-lap stints on the soft tyre.

13:48 @McLarenF1 We’re bringing the shutters down on today – a hydraulic leak means we need to change the engine. #TestingIsTesting

13:49 We were going to note that McLaren was still yet to grace us with its presence after lunch, and that explains it. Another tough day for the reformed alliance...

Button ends the day having logged seven laps, just one of them timed.

13:55 Grosjean is making his first appearance for the afternoon and, according to the timing screen, his first appearance for three hours. He joins Sainz and Ericsson, who are both racking up the laps, on track.

13:59 Back on track, Massa has improved on his personal best, clocking a 1m25.113s, three tenths off Hamilton's time.

14:01 With three hours of running left today, here's the full leaderboard.

1 Lewis Hamilton Mercedes 1m24.881s
2 Felipe Massa Williams 1m25.133s +0.252
3 Daniil Kvyat Red Bull 1m25.947s +1.066
4 Romain Grosjean Lotus 1m27.079s +2.198
5 Carlos Sainz Jr Toro Rosso 1m27.640s +2.759
6 Marcus Ericsson Sauber 1m27.802s +2.921
7 Kimi Raikkonen Ferrari 1m27.813s +2.932
8 Jenson Button McLaren 1m31.479s +6.598

14:02 Massa set his new fastest lap on the medium rubber, after a couple of stints on the softs earlier.

14:09 We've got our second red flag for the day. Apparently Sainz has stopped at Turn 10.

14:09 Carlos had been one of the busier drivers since lunch, taking his tally from 34 to 58 laps.

14:11 If you've just joined us for the afternoon session, don't expect to read about Jenson Button leaving the garage...

Barcelona F1 test: McLaren abandons programme on day one

14:17 We'd tell you more about the stoppage, but the circuit CCTV remains fixed on the grassy knoll on the outside of Turn 2. Our crisp-loving friend from earlier in the day hasn't returned.

14:20 The Toro Rosso is safely back in pitlane. Green flag flies again.

14:23 Here's the Toro Rosso returning to pitlane on the back of a truck. Looks like a racecar beneath the sheet which suggests a mechanical problem caused the stoppage.

14:24 Here's a snapshot of the day's headlines:

* Hydraulic leak sees McLaren end day early, having completed just seven laps
* Hamilton and Mercedes set searing pace but have yet to hit the track in the afternoon session
* Kvyat and Sainz Jr cause red flags in separate incidents
* McLaren is unsure whether Alonso will be fit in time to race in the season-opening Australian Grand Prix
* Rain shower hampers running in morning session

14:24 Massa wastes no time - he's moved to the top of the times with a 1m24.687.

14:25 Grosjean has also improved, by almost a second, to a 1m26.177.

14:26 Massa's fastest time came on mediums, which makes it the second-fastest time we've seen on the compound here in the last week or so - three-tenths down on what Rosberg achieved in Test 2.

14:27 Over the course of the afternoon, the track temperature has risen to 21.1C, air temperature is 14.7C. There's barely any wind, reasonable conditions for the teams to work in.

14:28 Interestingly, 90 minutes into the afternoon, we're still yet to see Mercedes.

14:34 Only Ericsson on track at the moment. The Sauber man is keeping it sauber on track and has been the busiest driver of the day, with 70 laps to his name.

14:37 Massa rolls out a 1m23.500s. Fastest time of the day and faster than any of the times we saw last week.

14:38 Massa's time was on softs, and he's now back in the pits after the little qualifying simulation.

14:40 Massa's lap is half-a-second faster than the fastest we saw last week, from Grosjean. If you want to recap the times from that test, here's our Test 2 round-up.

14:43 Here's the lap count for the day so far:

Ericsson - 75
Massa - 65
Sainz - 59
Kvyat - 56
Hamilton 48
Grosjean - 46
Raikkonen - 41
Button - 7

14:46 We told you earlier about some of the drivers enjoying support in the grandstand. Here's an LAT pic of those cheering for Kimi. We're not entirely sure what the sign means...

Win or lose, it's been a relatively quiet day from Ferrari. Kimi's completed 41 laps (only more than Button) and hasn't really caught the eye. But there's still two hours of running to go.

14:47 Kimi has just left the pits for the first time in a long time, no doubt to the delight of his fans. Commentator's summon?

15:03 Massa and Ericsson have the track to themselves as we enter the final two hours of running today. Massa is still quickest, after that three-lap soft tyre run earlier this afternoon.

15:04 We've just been visited by KARUN CHANDHOK, back from some more time in the field, with an update on Ferrari's progress and Massa's pace.

"Kimi looks quite good. Watching slow speed turn-in at the last chicane, Kimi looks really good, and at high-speed it looks reasonable but not as good as the Williams. But it looks like he's focusing more on race runs.

"The Williams looked really balanced on the softs, when Massa went for that laptime. It looks like on the medium they were doing race set-up work, they built in some understeer to protect the rear tyres; pushing the fronts and protecting the rears. When they went for the soft, the car looked really good for that one lap."

15:06 And for those of you following on the mobile app, here's a quick look at the timing screen...

1 Felipe Massa Williams 1m23.500s
2 Lewis Hamilton Mercedes 1m24.881s +1.381
3 Daniil Kvyat Red Bull 1m25.947s +2.447
4 Romain Grosjean Lotus 1m26.177s +2.677
5 Kimi Raikkonen Ferrari 1m26.327s +2.827
6 Carlos Sainz Jr Toro Rosso 1m27.261s +3.761
7 Marcus Ericsson Sauber 1m27.802s +4.302
8 Jenson Button McLaren 1m31.479s +7.979

15:07 Sauber confirms our suspicions that Ericsson is completing a race simulation. He's now turned 91 laps for the day.

@SauberF1Team: "Race simulation is on! Pit stop with a change from medium to hard tyres #F1 #ME9"

15:09 @MercedesAMGF1: "UPDATE: Failure in the Hybrid system keeping us in the garage currently. Crew working hard to fix it as we speak. #BackToWork #F1"

15:10 And that explains why we haven't seen Hamilton track since lunch. BEN ANDERSON had just spotted the Briton in his civvies and chilling in the Mercedes hospitality unit.

15:16 We've currently got Massa, Kvyat and Ericsson on track. Here's a shot of the pace-setter from LAT a little earlier today.

15:20 The only man on track, Marcus Ericsson has just reached his century of laps.

15:26 With just over 90 minutes to go, and Ericsson's race sim having seemingly just finished, here's a look at the lap count.

Ericsson - 103
Massa - 77
Sainz - 59
Kvyat - 58
Hamilton - 48
Grosjean - 48
Raikkonen - 45
Button - 7

15:27 Of that group, we've got Kvyat and Grosjean on track currently adding to their tallies.

15:35 Currently only Raikkonen on track, having recently emerged from the pits as Grosjean and Kvyat completed their stints.

15:42 Massa and Kvyat have left pitlane to keep Raikkonen company on the circuit.

15:44 With just over an hour to go, here are the day's top stories...

* Hydraulic leak sees McLaren end day early, having completed just seven laps
* Massa sets the pace for Williams, clocking the fastest lap set in Barcelona pre-season testing so far when using the softs
* Hamilton goes quickest on the medium in the morning but Mercedes has yet to run in the afternoon after a hybrid system failure
* Kvyat and Sainz Jr cause red flags in separate incidents

15:45 Today's other big talking point is Fernando Alonso, following his accident on Sunday.

Ron Dennis spoke to the press earlier and, if you missed the news, confirmed McLaren is unsure if the two-time world champion will race in Australia.

15:54 Felipe Massa has the track to himself at the moment, as the Brazilian clocks up his 85th lap in the Williams.

16:03 Massa dives into the pits as Kvyat and Grosjean head out. They are soon followed by Raikkonen.

16:05 @MercedesAMGF1: "That's our day done. Problem diagnosed as MGUK failure. Crew working hard to make sure we're back in business tomorrow."

16:10 So both McLaren and Mercedes fail to get any laps on the board this afternoon. Williams isn't having the same problems, though, with Felipe Massa back out on track and closing on his century.

16:15 Here's the latest lap count:

Ericsson - 105
Massa - 93
Kvyat - 66
Grosjean - 62
Raikkonen - 66
Sainz - 59
Hamilton - 48
Button - 7

16:17 Ericsson pops into third with a 1m25.330s on the softs tyres, 1.830s off the pace set by Massa.

16:20 A quick, late-afternoon trip to the roof provides interesting sights and sounds. For instance, Massa powering on past Button's forlorn pitboard, or Spanish dance jazz (as we're calling the genre) blasting over the grandstand PA.

16:23 Carrying the hopes of his nation this week and back out for the first time since causing the earlier red flag, Sainz has just recorded his best time of the day in the 'brand new' Toro Rosso, a 1m26.962s.

16:29 Bang on 30 minutes remaining for the day, here are the times following Ericsson and Sainz's recent improvements.

1 Felipe Massa Williams 1m23.500s
2 Lewis Hamilton Mercedes 1m24.881s +1.381
3 Marcus Ericsson Sauber 1m25.330s +1.830
4 Daniil Kvyat Red Bull 1m25.947s +2.447
5 Romain Grosjean Lotus 1m26.177s +2.677
6 Kimi Raikkonen Ferrari 1m26.327s +2.827
7 Carlos Sainz Jr Toro Rosso 1m26.962s +3.462
8 Jenson Button McLaren 1m31.479s +7.979

16:32 During his most-recent stint, Massa joined Ericsson in the 100-lap club. He's now on 101 to Ericsson's 112, next best is Sainz on 70.

16:37 Some more from KARUN CHANDHOK from his visit to the media centre a little earlier, about two of the drivers currently lapping the circuit.

"Grosjean on the softs was pushing the tyre really hard to see how much life he could get out of it. On the first two laps, he was very aggressive, more so than in a race, trying to see the limit of the tyre before calming down.

"The Toro Rosso seems to be having all sorts of weird driveability issues. It seems to break traction and the rear steps out of line more often than any other car. I wonder if they’re trying some experimental throttle maps, because it looks very different to the Red Bull on throttle."

16:40 On the supersofts, Ericsson has moved to P2 with a 1m24.610s.

16:46 Ericsson dives into the pits, leaving just Raikkonen and Sainz out on track as we went the final 15 minutes of the session.

16:50 KARUN CHANDHOK confirms that that last lap from Marcus Ericsson was a planned super-soft run having spoken to the Swede just before the run.

16:52 Ericsson is back out on track and after bolting on another set of supersoft tyres improves his best to a 1m24.276, 0.776s off the pace set by Massa.

16:56 Five minutes left, now or never for any late qualifying simulations.

17:01 And that's the chequered flag! Massa finishes the day quickest, with Ericsson 0.776s off the pace in second. Hamilton ends up third.

17:01 Here's how they finished:

1 Felipe Massa Williams 1m23.500s
2 Marcus Ericsson Sauber 1m24.276s +0.776
3 Lewis Hamilton Mercedes 1m24.881s +1.381
4 Daniil Kvyat Red Bull 1m25.947s +2.447
5 Romain Grosjean Lotus 1m26.177s +2.677
6 Kimi Raikkonen Ferrari 1m26.327s +2.827
7 Carlos Sainz Jr Toro Rosso 1m26.962s +3.462
8 Jenson Button McLaren 1m31.479s +7.979

17:03 And here's the final lap count:

Ericsson - 122
Massa - 103
Sainz - 86
Raikkonen - 80
Kvyat - 75
Grosjean - 75
Hamilton - 48
Button - 7

17:52 Thanks for joining us on AUTOSPORT Live today. We'll be back on deck tomorrow morning. Stay tuned for plenty of analysis from Barcelona throughout the evening.

Today's report: Felipe Massa fastest on first day of final test

P Driver Team Time
1  Felipe MassaWilliams 1m23.500s
2  Marcus EricssonSauber 1m24.276s  +0.776
3  Lewis HamiltonMercedes 1m24.881s  +1.381
4  Daniil KvyatRed Bull 1m25.947s  +2.447
5  Romain GrosjeanLotus 1m26.177s  +2.677
6  Kimi RaikkonenFerrari 1m26.327s  +2.827
7  Carlos Sainz JrToro Rosso 1m26.962s  +3.462
8  Jenson ButtonMcLaren 1m31.479s  +7.979
All timing unofficial. Updated: 16:51 GMT
Mainly cloudy High Temp: 12°C / 54°F
Track: Dry
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