07:50 Good morning and welcome to day four from Jerez.

The weather forecast for the final day of F1 testing in Spain has changed several times this week, but we've got a bit of rain and a wet track at the moment.

08:01 We're green and Rosberg immediately heads out. Will Mercedes complete the most laps again today?

08:02 It's pretty dark, more like sportscar conditions than Formula 1!

08:03 Rosberg comes straight in. Not a big surprise.

08:04 There are a few changes to get excited about today, including the Caterham debut of Kamui Kobayashi - his first official F1 session for over 12 months.

Here is the full run-down of day four's drivers:

Daniel Ricciardo, Red Bull
Nico Rosberg, Mercedes
Fernando Alonso, Ferrari
Kevin Magnussen, McLaren
Daniel Juncadella, Force India
Adrian Sutil, Sauber
Daniil Kvyat, Toro Rosso
Felipe Massa, Williams
Kamui Kobayashi, Caterham
Jules Bianchi, Marussia

08:04 Sutil now heads out for Sauber.

08:06 Massa takes the Williams out as well.

08:07 Of course, it's not the first time in 12 months Kobayashi has actually driven an F1 car.

He tested a 2010 Ferrari F1 car at Fiorano in May last year, and then two months later drove another Ferrari during a Moscow City Racing demonstration event.

That didn't end so well though - he lost control on the wet surface and hit the barriers.

08:08 Sutil and and Massa both come in, so no times recorded yet.

08:10 And Alonso takes the Ferrari out. He was the only man able to get among the Mercedes-engined runners yesterday.

08:10 Rosberg goes back out.

08:12 Alonso comes back in as Ricciardo goes out. Can Red Bull get some decent running today? The team only managed three laps yesterday.

08:14 Rosberg has come back in. Ricciardo has also made it back to the pits, while Toro Rosso rookie Daniil Kvyat heads out.

08:15 Earlier in the week, Toro Rosso boss Franz Tost said he felt the 2014 regulations won't prevent rookie drivers from showing well:

"For sure it's not easy this year, but it's always the same story. The cleverer a driver is the easier he adapts to any changes. And don't forget, especially this year, the drivers will be supported by the engineers. They will decide which [engine] map to use.

"I don't see it as a disadvantage to start in F1 as a young driver this year, although everything is not as easy as in the past when we just had the V8s."

08:16 Kvyat comes in as Rosberg heads out for the third time in just over 15 minutes.

08:19 Quick summary of the week so far:

* Ferrari sets the pace early with Kimi Raikkonen.
* McLaren takes control on days two and three with Jenson Button and Kevin Magnussen.
* Mercedes look strong, covering more laps than anyone despite a front wing failure for Lewis Hamilton on day one.
* Renault-engined teams in trouble, with Red Bull failing to have any meaningful running on the first three days.

08:25 Kobayashi has gone out for his first run in the new Caterham.

08:26 Sutil comes out again. Nine cars have already been on-track, including all three Renault-engined machines, but no times have yet been recorded.

08:29 Ricciardo heads out again as Sutil records the first flying lap of the day at 1m53.700s.

08:31 Kvyat heads out too. This is Renault's most promising morning this week already!

08:33 Sutil has now recorded 1m50.885s. The best of the test so far, in the dry, is Magnussen's 1m23.276s, which he set yesterday.

08:34 And Ricciardo does a 1m45.374s. A Red Bull tops the timesheet for the first time this week!

08:36 Sutil improves again, but is still second. Alonso and Kobayashi have also gone out.

08:37 Sutil improves again. Ricciardo is back in, but is still fastest.

08:39 It's very early this morning still, but the simple fact that Red Bull is on track and running is encouraging for the champion team, such has been its plight this week.

JONATHAN NOBLE got the inside line on Red Bull and Renault's problems yesterday for his Thursday test feature:

Alarm bells ringing at Red Bull

08:40 We assessed what the drivers have been making of F1 2014 yesterday, and Sutil had this to say:

"It's so different and you can feel it in every gear. It's not about using all the rev band anymore. The torque is in the middle of the rev band so you can sometimes shift a bit earlier, or use different gears in a corner, it doesn't really make a difference.

"So the engine is a lot more powerful in the rev band than the V8. The V8 was more operating between 15 and 18,000rpm so you always had to keep the revs up.

"Also we have eight gears, so you never run into a limiter at the end of the straight, you can go at almost 400km/h with these gears so it's very different, a massive change in every direction."

08:42 Sutil has pitted and we now only have Rosberg out on the circuit.

08:44 Force India's Daniel Juncadella reports back on the track conditions.

@clubforce: "Dani reports standing water between turns 5 and 6 but 'not too much' following his opening lap at the wheel of a VJM07. #FeelTheForce"

08:45 And Rosberg now goes to the top of the times, with 1m38.778s.

08:47 Juncadella has got a test and reserve deal with Force India this season.

He's the 2012 European Formula 3 champion and will dovetail his new F1 commitments with racing for Mercedes in the DTM again.

If you want to check out the full statistics from the young Spaniard's career so far, including all his results in car racing, here's his page in our FORIX database - the most comprehensive motorsport stats resource on the internet and available as part of the AUTOSPORT subscription package.

08:48 Ricciardo has already done more laps today - five - then he managed yesterday!

08:50 Rosberg has got down to 1m38.157s. Only three drivers have recorded a time so far, though Bianchi has just taken the Marussia out.

08:51 AUTOSPORT has expanded around the globe in recent years, and if you want to keep up with the Jerez F1 test in Arabic, our Middle Eastern arm AUTOSPORT.me is also covering the test live.

08:54 Bianchi is in, Kvyat and Sutil head out, while Rosberg continues his run. We've got used to the Mercedes W05 lapping as others sit in the pits this week. Rosberg is currently doing 1m38s.

08:56 Kvyat comes past the pits. The Toro Rosso still doesn't sound 100 per cent, but it is at least running.

08:57 And Kvyat gets a lap on the board - 1m45.817s to go third.

09:00 The Toro Rosso improves again and is closing on Sutil's Sauber, which has just set its own PB. Rosberg is still lapping in the 1m38s, six seconds quicker than anyone else.

09:02 Kvyat records a 1m44.016s and is firmly second at the moment. Massa has taken the Williams out too.

09:04 Kvyat is in - happily under his own steam. Rosberg has also pitted, leaving Sutil and Massa on track.

09:04 Magnussen takes the McLaren out as Massa goes second with 1m40.020s.

09:06 Massa was a happy man after his first taste of the new Williams on Thursday - and he has found other positives at his team too.

In fact, the Williams motorhome staff were the subject of his biggest praise...having been a big sceptic of English food after so long in Italy.

"Honestly, I am happy for the food here – it is better than expected here. Not in England itself, but in the motorhome," he said.

"With the motorhome I would say I am very happy with the food – but in England I don't think it will change!

"And the coffee is much better in Italy, so maybe I need to buy a coffee machine for the team."

09:10 More pitstops, so now it is just Kobayashi out on track.

09:10 And no sooner have we typed that Bianchi heads out in the Marussia.

09:13 Rising British star James Calado is clearly reading AUTOSPORT Live this morning as he's just got straight onto Twitter to defend his nation's culinary honour:

"@Felipe1Massa nothing wrong with English food mate!!"

09:13 Kobayashi sets a 1m50.299s, so we now have six drivers who have set a time.

09:14 Make that seven as Bianchi does 1m48.192s to go ahead of the Caterham.

09:17 Rosberg is back out and Alonso follows. The Ferrari has yet to set a time this morning.

09:20 Rosberg had this to say on the change from the 2013 V8s to the new 1.6-litre turbos:

"The car feels OK, not too different. It is heavier, so it feels like last year with a lot of fuel, and of course there is a lot less downforce.

"The engine is a bit different and we have higher gears, so in the hairpin you're going to be using third gear instead of first gear sometimes."

It's interesting that he feels the Mercedes is "not too different" as many drivers have been emphasising the difference between the 2013 and '14 cars. Is that indicative of how much more prepared Mercedes is compared to the others?

09:23 The Mercedes is back down into the 1m38s and 1m39s. Almost every flying lap Rosberg has done this morning has been quicker than the best of the other runners.

09:25 The 2014 Mercedes is the main cover star of this week's edition of AUTOSPORT magazine.

It's a new season launch special, containing in-depth analysis of and Gary Anderson's verdict on the leading teams' new designs.

We examine the implications of Ron Dennis's return to the helm of McLaren, talk to Paddy Lowe about Mercedes' prospects in the new era and take a detailed look at the issues Ferrari must address this season.

There are also interviews with Nico Hulkenberg, Valtteri Bottas and Adrian Sutil.

If you haven't already been to a newsagent, you can read the digital version here.

09:25 Magnussen jumps to third with 1m40.702s. He topped yesterday's running in the dry without pushing too hard.

09:28 JONATHAN NOBLE also reckons his magazine column this week contains "the most animals that have ever appeared in the first sentence of anything in AUTOSPORT".

It probably would take some beating, as it reads...

"An anteater, a proboscis monkey, a crooked crab and a beluga whale walk into a bar. The bartender looks up and says, 'Is this some kind of Formula 1 joke?'"

You can find it on page 11.

09:28 Magnussen makes a quick pitstop and heads back out. Rosberg and Massa are the other two cars out there and they are running quite close together.

09:30 Fantastic from Massa. As he closes on Rosberg he fishtails out of the last corner to record 1m39.313s, a new PB.

09:32 Here's more from Massa on how happy he is at Williams.

09:32 But Magnussen now goes second, 1m38.391s. Like Massa, he is on the Pirelli inters.

09:34 Sutil and Kobayashi are now out too, so we have five on track.

09:34 Four again, as Massa comes in.

09:35 Kobayashi improves and moves to sixth.

09:38 Magnussen pits briefly and heads straight back out. Juncadella isn't far behind him in the Force India.

09:39 Kobayashi continues to bring his times down and has now managed a 1m44.859s to go fifth.

09:41 Alonso heads out. Only he and Juncadella have yet to set a time so far.

09:41 Sutil jumps past Kobayashi with 1m44.403s, but Juncadella then comes across the line and goes a fraction faster. That puts him fifth.

09:43 Rosberg looks like he is seeing how the Pirelli inter wears and degrades. He's still out there, but now lapping in the 1m41s. Magnussen may be doing the same thing for McLaren.

09:47 Alonso just had a huge moment on the kink approaching the final hairpin, but he has now gone fourth, 1m40.194s. Juncadella has also improved.

09:49 The looks and sounds of the 2014 F1 cars have caused fervent debate all week, but we've yet to hear much from those who will spend the season in them.

Yesterday KEVIN TURNER gathered the views of the men behind the wheel, hearing from Fernando Alonso, Jenson Button, Nico Rosberg, Valtteri Bottas, Esteban Gutierrez, Sergio Perez and Adrian Sutil to get a sense of how different the new cars feel from the cockpit.

The drivers' verdict on F1 2014

09:51 Worth noting that Alonso set his time on the Pirelli wet, whereas the top times have been coming on the intermediate. Different programmes obviously being tried by the teams.

09:55 Rosberg is the only car still out on track as he continues what could be a race simulation.

09:57 SAM TREMAYNE has just come back from some trackside viewing. He reports the Mercedes looks impressive. More on his verdict on the 2014 cars later.

09:59 Rosberg finally pits. He has completed 42 laps, which is twice as many as the next best, Sutil on 21.

09:59 Rosberg goes straight out again so his long run is not over.

10:04 And on his fresh rubber, Rosberg improves his best time, now 1m37.580s.

10:06 Rosberg in and back out again. Massa has joined the Mercedes and McLaren on track, and now Ricciardo heads out too.

10:09 Massa improves to 1m39.256s, but is still third.

10:13 A quick rundown of what people have done so far:

1 Rosberg (Mercedes) 1m37.580s, 49 laps
2 Magnussen (McLaren) 1m38.391s, 19 laps
3 Massa (Williams) 1m39.256s, 13 laps
4 Alonso (Ferrari) 1m39.999s, 16 laps
5 Juncadella (Force India) 1m41.925s, 8 laps
6 Kvyat (Toro Rosso) 1m44.016s, 8 laps
7 Sutil (Sauber) 1m44.224s, 21 laps
8 Kobayashi (Catherham) 1m44.859s, 15 laps
9 Ricciardo (Red Bull) 1m45.374s, 7 laps
10 Bianchi (Marussia) 1m48.192s, 5 laps

10:15 Massa is closing up behind Magnussen, having already gone by Alonso.

10:15 And Magnussen lets the Williams by, even though both lapped in the 1m41s last time around.

10:17 Kobayashi, who came out not far behind Rosberg, sets a PB of 1m44.131s as the Mercedes draws away from his Caterham.

10:20 SAM TREMAYNE reports that Magnussen looked like he was pushing pretty hard while our man was stood trackside.

10:21 Though yesterday Magnussen was adamant that his first day on official duty for McLaren wasn't "balls to the wall". He was quickest, though...

10:22 Kobayashi is bringing his times down again and has now moved ahead of Kvyat, who we've not seen for a while, to go fifth fastest.

10:24 McLaren can't keep itself out of the headlines so far in 2014: Dennis back, Boullier brought in, and this week a lot of focus on its innovative rear suspension 'blockers'.

Last night AUTOSPORT revealed that rival teams have started making enquiries to the FIA about the McLaren design's legality with a view to starting work on their own versions, though as GARY ANDERSON explained in his analysis, copying it won't be easy.

10:24 We've now got a busier track than we've seen for most of this week, with Rosberg, Magnussen, Massa, Juncadella and Kobayashi currently circulating.

10:26 Once again, we spoke to soon, as Juncadella and Kobayashi both come in. Last time around, Massa, Magnussen and Rosberg all lapped within a second of each other.

10:30 Magnussen has impressed so far at Jerez and the man himself thinks 2014 is not a bad time to be joining the F1 grid:

"I wouldn't say it is an advantage being a rookie. But it is not as big a disadvantage as in other years.

"I think it is the right season, a good season, to come in. Because this car is so different the driving is going to be different, and everyone will have to learn that again.

"But I am a rookie, I will still have a lot to learn that other drivers know very well. So working with an F1 team and in a race weekend, all these things I'm going to have to learn.

"I'm not underestimating anything, but I think it's a good year to come in as a rookie."

10:31 Magnussen and Massa have pitted, so guess who is left on track? Yes, it's Rosberg, who has just completed his 61st lap of the day.

10:33 Alonso heads out. Ferrari seems to be following quite a different programme to the Mercedes teams, but it would be nice to see what laptime he could do.

10:38 Alonso in and out, Sutil also takes the Sauber onto the circuit.

10:40 Alonso brings the Ferrari back in again. Kobayashi heads out for Caterham. Rosberg has now completed 66 laps and has just set a best first sector after a quick stop.

10:42 It's a 1m37.877s for Rosberg. Not quite his best, but still faster than anyone else has done today.

10:43 But this time he does go faster - 1m37.310 - as he closes on Sutil.

10:46 Rosberg passes Sutil and Juncadella heads out.

10:47 Magnussen has gone out again in the McLaren MP4-29.

10:49 Juncadella improves to 1m41.400s, but remains fifth.

10:50 The Force India improves again, now down to 1m41.132s. Rosberg is currently in the 1m38s, Magnussen in the 1m39s.

10:53 Are you still sore over F1's adoption of double points for the season finale? (AUTOSPORT is)

Yesterday NASCAR went a fair few steps further than F1 when it announced that its title fights would now come down to a single winner-takes-all race at the end of the year.

So what you score in the first 35 races of the 36-round Sprint Cup season is just to decide the four drivers who are eligible for the title in the Homestead shootout.

We've just opened a debate about the new format on the AUTOSPORT Facebook page, so feel free to comment.

10:56 Juncadella does a 1m41.133s and a 1m41.261s to follow up his 1m41.132s. Now that is consistent!

10:57 And Juncadella has a nice slide out of the last corner. The time is still a 1m41.780s.

10:58 Rosberg, back in the 1m37s, is closing on Magnussen.

11:01 OK, we realise we may be tempting fate, but...We're now at midday local time, after three hours of running, and we haven't had a red flag. Given how much trouble some of the teams have had here, and how tricky the conditions are, that's a good effort.

11:02 Rosberg lowers his best mark once again, 1m36.951s. He's opening out that gap over the rest and has now done 79 laps.

11:08 Rosberg still lapping in the 1m37s. We've now lost count of how many laps he has done that are quicker than Magnussen's 1m38.391s effort.

11:10 The fastest five runners are now out on track. Will Alonso set a new PB? It's a long time since he did his 1m39.999s.

11:12 Magnussen brings the McLaren back in, and Massa pits the Williams.

11:12 Sutil has gone out so we now have four cars on rack.

11:13 Alonso does indeed go faster, 1m39.477s, but is still behind the three Mercedes-powered cars.

11:16 Alonso is now on the inters, but is lapping considerably slower than Rosberg at the moment. Juncadella's consistency in the Force India is still impressive.

11:19 Rosberg is currently in the 1m38s, Alonso in the 1m40s, and Juncadella in the 1m41s. Sutil is still out there, but is doing 1m44s - the Sauber has seemed to lack pace this week.

11:21 Sauber has been having trouble with its braking system at Jerez, which could explain its laptimes. Better for the drivers to put on mileage at a slower pace than risk throwing it off (as Gutierrez did on day two).

11:22 Rosberg pits. He has now completed an impressive 91 laps. The next best is Magnussen's McLaren on 43.

11:27 Kobayashi has gone out, so we have Caterham, Sauber and Ferrari circulating at the moment.

11:28 Juncadella goes out, Kobayashi comes back in.

11:30 GARY ANDERSON, whose Formula 1 design career including the race-winning Jordan and Stewart cars of the 1990s, is part of AUTOSPORT's technical expert team and has been writing analysis pieces and features for us all week at Jerez.

In his Thursday night round-up, he tackled topics including why the Ferrari sounds different on downchanges to its rivals, which cars are already looking sharpest from trackside, and Red Bull and Renault's prospects of a quick recovery.

11:30 And they swap, the Caterham returning to the circuit and the Force India pitting.

11:33 And the track suddenly seems quiet, with just Kobayashi lapping in the Caterham.

11:37 Kobayashi pits, but goes straight back out again.

11:40 Alonso's Ferrari now joins Kobayashi.

11:42 Kobayashi pits, but Massa takes the Williams out. The FW36 has had a pretty good week so far.

11:45 Alonso heads out on an otherwise clear track and duly hits the front with a 1m35.334s, set on inters.

11:48 Alonso stays out for the fourth lap of this run, but he's all alone. We suspect other teams may be breaking for unofficial lunch.

11:49 Mercedes confirms our suspicions:

@MercedesAMGF1: "Time for a well-earned break; would somebody please get @nico_rosberg a plate?!"

11:49 Does this mean Kamui has to watch as his Caterham crew eat?

@CaterhamF1: "Lunchtime on day 4 in Jerez. So far we have completed 41 laps with Kamui in the car & we're keeping him strapped in so we can add to that..."

11:56 As Alonso clocks up the laps, here is day three pacesetter Kevin Magnussen on his and McLaren's goals for the final day at Jerez:

"I'm sure there is a lot of performance to come. That will never stop - in F1 it never does - but I'm sure we'll improve this week too.

"The important thing is to get a good understanding of where to improve coming away from here."

The Dane was clearly enjoying himself this morning, regularly playing with oversteer in the wet conditions.

12:01 Alonso, who hit a half century of laps just before midday, has company in the form of Caterham's Kamui Kobayashi.

12:02 Magnussen - himself nearing the 50-lap mark - heads out.

12:08 Race run done for Nico Rosberg, and he's handing over driving duties for the afternoon:

@nico_rosberg: "Cool, day 4 of testing & already completed a full race practice. Will now hand over the car to @lewishamilton."

12:13 More changes afoot at McLaren, here's JONATHAN NOBLE's story on the latest personnel moves:

McLaren reshuffles its aero department

12:13 That change, incidentally, is to even up mileage.

Rosberg was able to rack up 91 laps this morning, to add to his 97 from day two.

Hamilton only managed 18 before suffering a front wing failure on day one, and then added 62 yesterday.

12:14 Magnussen pits, but Alonso is still out. A very good run this for the Ferrari man, who hasn't dropped below the 1m37/38s bracket.

12:21 Here's the full report from this morning at Jerez, as Fernando Alonso and Ferrari go top but Mercedes rolls on and on and on:

Jerez test day four morning report and results

12:22 Alonso finally pits, but he doesn't box - he comes straight through and to the end of the pitlane for a practice start. It's not great, but he is away once more.

12:23 Alonso clearly on it - he gets sideways coming into the pitlane. It's another straight-through job, and he rejoins courtesy of another practice start.

12:26 As we move into the afternoon, here is a quick rundown of the order (and lap count) so far on the final day:

1. Fernando Alonso (Ferrari) 1m35.334s, 64 laps
2. Nico Rosberg (Mercedes) 1m36.951s, 91 laps
3. Kevin Magnussen (McLaren-Mercedes) 1m38.391s, 49 laps
4. Felipe Massa (Williams-Mercedes) 1m39.256s, 34 laps
5. Daniel Juncadella (Force India-Mercedes) 1m41.132s, 32 laps
6. Kamui Kobayashi (Caterham-Renault) 1m43.193s, 45 laps
7. Daniil Kvyat (Toro Rosso-Renault) 1m44.016s, 8 laps
8. Adrian Sutil (Sauber-Ferrari) 1m44.234s, 43 laps
9. Daniel Ricciardo (Red Bull-Renault) 1m45.374s, 7 laps
10. Jules Bianchi (Marussia-Ferrari) 1m48.192s, 5 laps

12:31 Quick round-up of the fourth and final day of Jerez testing so far:

* Rosberg runs first race simulation of 2014
* Alonso and Ferrari top timesheets at midday
* Kobayashi gets his first run in the Caterham CT05
* Bianchi likewise heads out in the Marussia MR03 for the first time
* Red Bull and Toro Rosso complete just a handful of laps
* Juncadella impresses with his first run in Force India

12:32 EDD STRAW, down with the fans at the final chicane, says that Alonso has been keeping the crowd entertained.

Some spectacular sliding in the right-left-right section drew enthusiastic applause, apparently.

12:37 While Red Bull and Toro Rosso have racked up a handful of laps (15 to be precise), one Renault-powered team is at least clocking up the laps:

@CaterhamF1: "45 laps now for @kamui_kobayashi who continues to pound round, adding to his mileage.

Don't tell him, but there's katsu curry for lunch...."

12:38 Red Bull calls time on its troubled Jerez test:

@redbullracing: "We've finished testing for the day. All focus now shifts to Bahrain. Full update to come shortly."

12:41 Here was Vettel speaking before pre-season kicked off...

"The bigger the changes the more time it takes for everyone – drivers, engineers, people in the factory – to adapt, so we will probably see more retirements than we are used to.

"We understood the cars more in the past and now everything is new, so I think mistakes will happen for everyone.

"We have been on an incredible run and we will try to do it again to make it five (titles in a row), but at the moment expectations are low, as we don't know what's coming.

"We've had a good run but now it's a blank sheet of paper, so we will have to wait and see."

12:44 Magnussen sets a new personal best, but stays third, just as Alonso lights up the timing screens by going fastest of all in sector one...

12:46 Alonso pits, but Magnussen improves once again.

He's now broken through the 1m38s barrier, moving to within 2.5s of today's benchmark.

12:49 Six consecutive personal bests now from Magnussen, who has shaved a few tenths of a second off every time he has crossed the line. Impressive stuff.

His latest effort is a 1m37.391s, which moves him onto the tail of Nico Rosberg's Mercedes.

12:51 SAM TREMAYNE spent the morning at the trackside with GARY ANDERSON getting some hints of how the individual cars are handling as the mileage becomes more serious. Here's what they discovered:

Trackside analysis: Mercedes rises early

12:52 Magnussen brings that impressive run to a close, and we have quiet on circuit.

12:58 Fernando Alonso heads for lunch, and is duly mobbed by hundreds of Spanish fans on the short walk between the team's garage and its hospitality unit.

13:02 The silence is broken by Kamui Kobayashi, who heads out in the Caterham CT05.

It's been a good day so far for driver and team, with 51 laps already on the board.

13:05 Here is the full story on Red Bull's early exit after a troubled Jerez test:

Red Bull ends Jerez test early

13:10 Our colleagues at LAT captured this from one of Daniel Ricciardo's early laps.

The bright orange spark in the top left corner isn't a camera glitch - it is something flying off the back of the RB10.

13:13 Magnussen and Massa head out for McLaren and Williams respectively.

13:14 Incidentally, today is already the busiest day at Jerez.

On day one, a collective 93 laps were completed. That rose to 331 and then 340 on days two and three respectively.

Just past the halfway mark of day four, we're already past 400 and counting.

13:16 Here's another afternoon statistic: Kamui Kobayashi, with 53 laps completed, has racked up more mileage today than every Renault-powered team managed across the opening three days of this first pre-season test.

13:19 Massa is up to speed quickly, posting a new personal best - a 1m39.163s - on his second flyer.

He doesn't stop there either - next time round is a 1m38.532s.

13:22 Sutil improves too, but it is still only a 1m42.549s.

13:24 And two more improvements. Magnussen goes second with 1m35.769s and Massa improves again, to 1m38.239s.

13:25 More improvements, and this time at the top of the timesheets.

Magnussen deposes Alonso with a 1m34.084s. Will the Dane top his first two days as a McLaren driver?

13:27 Into the 1m33s now for Magnussen, leaving him almost 1.5s clear of Alonso.

Scratch that, he's 1.7s clear now as he dips down to a 1m33.619s next time around.

13:30 Magnussen set those times on the special Jerez compound.

Bianchi heads out for Marussia shortly after the Dane crosses the line, but the MR03 is shod with wet tyres.

Daniel Juncadella has also headed out on track.

13:31 Times tumbling here.

Magnussen improves to a 1m33.350s, while Juncadella slots into third with a 1m36.300s.

13:33 Juncadella, on the super soft tyre, has a massive wobble heading out of the final hairpin.

He shakes off the bout of oversteer however and crosses the line in 1m33.119s, sending Force India to the top of the timesheets.

13:36 Interesting battle this. Juncadella and Magnussen are on opposite sides of the track, but they keep trading blows.

The latter, on the special Jerez compound rather than super softs, wrests back the advantage with the day's first sub-1m33s lap.

Juncadella has pace in reserve though, and stops the clock at 1m31.719s next time around.

13:38 Kobayashi, Sutil and now Massa have all headed out.

13:39 While a dry line has gradually emerged, the track remains quite damp in places. It's likely to stay that way too, at least while temperatures remain below 14 degrees C.

13:41 Bianchi heads back out, this time on inters. Sutil is on mediums, Massa on the Jerez compound. It has probably just moved decisively into slick territory.

13:44 Massa improves, but we're not sure his 1m36.783s should count as our scouts tell us he cut the chicane...

13:45 Bianchi jumps from 10th to sixth after a 1m40.966s.

13:46 Which leaves Red Bull rooted to the bottom of the timesheets.

13:47 More breaking news from the paddock: the FIA has been in contact with the teams over some concerns it has about the 2014 noses (and no, unfortunately, those concerns are not to do with the appearance). Read more here.

And if you want a thorough explanation of how some subtle regulation tweaks caused such a significant change to the appearance of the cars for this year, check out this piece from @ScarbsF1:

F1 2014 tech: aero controversy explained

13:50 Red Bull is also bottom of today's lap count:

1. Daniel Juncadella (Force India-Mercedes) 1m31.719s, 45 laps
2. Kevin Magnussen (McLaren-Mercedes) 1m32.260s, 82 laps
3. Fernando Alonso (Ferrari) 1m35.334s, 71 laps
4. Felipe Massa (Williams-Mercedes) 1m36.069s, 48 laps
5. Nico Rosberg (Mercedes) 1m36.951s, 91 laps
6. Jules Bianchi (Marussia-Ferrari) 1m40.966s, 10 laps
7. Adrian Sutil (Sauber-Ferrari) 1m42.549s, 51 laps
8. Kamui Kobayashi (Caterham-Renault) 1m43.193s, 54 laps
9. Daniil Kvyat (Toro Rosso-Renault) 1m44.016s, 8 laps
10. Daniel Ricciardo (Red Bull-Renault) 1m45.374s, 7 laps

13:51 We should shortly have another name to add to that list, as Lewis Hamilton heads out for Mercedes.

If you missed it earlier (see 1208), the Briton is taking over from Rosberg in order to balance mileage between the two men.

13:52 Hamilton has company on his first lap of the day, as Alonso rejoins for Ferrari.

13:55 Hamilton's first effort, a 1m40.227s, moves him up to sixth.

13:56 A useful comparison from Mercedes:

@MercedesAMGF1: "For those asking about comparative driver mileage: @nico_rosberg has done 188 laps so far this week, @LewisHamilton has 80."

14:03 On the sixth timed lap of this current run, Alonso improves to a 1m34.331s but stays third.

14:06 Alonso is tucked into Sutil's slipstream down the main straight, and duly dives down the inside under braking for Turn 1.

The German still improved that lap though, moving into sixth and above Hamilton - who is also swarming over the back of the Sauber. Hamilton executes a move along the back straight.

14:07 More improvements for Alonso, as consecutive bests take him down to a 1m32.665s, now within one second of the outright pace.

14:08 Magnussen and Juncadella have both headed out for their respective teams.

14:09 Alonso, now on the 10th lap of this medium-shod run, jumps to second with a 1m32.132s.

14:10 Into fourth now for Hamilton, who jumps ahead of team-mate Rosberg by stopping the clock on a 1m36.053s.

14:11 Alonso hits the front, setting a new benchmark of 1m31.551s.

Moments later Juncadella - again on the super softs - comes with 0.027s of demoting him.

14:17 More back and forth between Alonso and Juncadella.

The latter hits the front with a low 1m31s, shortly before having to pick off Hamilton's Mercedes.

Alonso responds though, and moves back to the front with a 1m31.804s.

Moments later, Magnussen and Massa both improve, pushing Hamilton down to fifth.

14:18 Red flag - we have a Sauber in the gravel.

14:20 Sutil has gone off backwards at the final chicane.

14:23 The German crashed yesterday, losing control of the rear of his C33 at Turn 7.

He later took the blame for the accident.

14:27 Sutil's C33 is back in pitlane, which means we should restart shortly.

14:28 Very shortly. Back to green.

14:29 Incidentally, that red came as Alonso moved onto the 17th lap of a stint on mediums, which featured several improvements and yielded the fastest time so far today. He had just set that time - a 1m30.861s - when Sutil went off.

14:31 Marussia out on super softs. Bianchi needs to find around 2.5s to ensure Red Bull finishes bottom of the pile after four days at Jerez.

14:34 Juncadella, Massa, Magnussen and Hamilton are all out.

14:37 Green paint all over the timesheets as Juncadella, Massa and Hamilton all improve.

14:40 Improvements again next time round, headlined by Juncadella, who moves back to the top with a 1m30.437s set on the hard compound.

Massa jumps up into second, while Hamilton leapfrogs Magnussen to sit fourth.

The latter duo are on mediums.

14:41 His spell doesn't last long though, as Massa sets two laps in the sub 1m30s bracket to put Williams on top.

14:44 We're definitely into proper running and mileage now, which means tumbling laptimes and - something not entirely expected on day one - traffic.

Hamilton was under pressure from Juncadella earlier, eventually surrendering position to the Spaniard down the back straight.

14:50 Alonso hits the front once more, but for all of thirty seconds, as Massa responds to depose his former Ferrari team-mate with a 1m29.023s.

14:52 We have a second red of the afternoon.

14:53 Massa, Alonso, Hamilton and Magnussen were all out on track. We're not sure which of that quartet has prompted this stoppage.

14:53 It's Magnussen. The Dane is parked at the chicane.

14:56 Scratch that, he's facing the wrong way. Looks like he's lost the rear of the MP4-29 coming through the left-hander. His car has rotated 180 degrees but is still on the asphalt, which means no damage.

14:56 Magnussen gestures that he's OK to the arriving McLaren crew, one of whom gives him a conciliatory pat on the back. Given the proximity to the pitlane, this shouldn't take too long.

15:01 Which is a good time to given you a rundown of the order and lap count with one hour remaining of the final day:

1. Massa (Williams-Mercedes) 1m29.023s, 65 laps
2. Alonso (Ferrari) 1m29.290s, 96 laps
3. Juncadella (Force India-Mercedes) 1m30.437s, 63 laps
4. Hamilton (Mercedes) 1m30.835s, 30 laps
5. Magnussen (McLaren-Mercedes) 1m31.804s, 102 laps
6. Rosberg (Mercedes) 1m36.951s, 91 laps
7. Sutil (Sauber-Ferrari) 1m39.941s, 57 laps
8. Bianchi (Marussia-Ferrari) 1m40.966s, 14 laps
9. Kobayashi (Caterham-Renault) 1m43.193s, 54 laps
10. Kvyat (Toro Rosso-Renault) 1m44.016s, 8 laps
11. Ricciardo (Red Bull-Renault) 1m45.374s, 7 laps

15:03 The MP4-29 is back and being unloaded below our spot in the media centre. We're back to green for the final hour of this final day at Jerez.

15:07 Unsurprisingly there's a queue of cars waiting to rejoin. Massa, Juncadella, Sutil and Bianchi all head out immediately.

15:10 Red Bull will end the test at the foot of the timesheets for the week - Bianchi comes round in a 1m37.699s on his first flyer of this final hour.

The RB10's best? A 1m38.320s on day two.

15:15 Little wonder, given that last statistic, that Daniel Ricciardo was the subject of such a media scrum earlier this afternoon.

The Australian insists there is no need to panic however, saying the team still "has time on our side".

15:16 Bianchi improves again, jumping up to sixth after registering a 1m35.589s.

15:22 Massa, Alonso and Hamilton - all three of whom have had long runs interrupted by red flags - are our three men currently out on circuit.

15:25 Practice starts for Massa, which means Magnussen has to wait a few seconds before being released onto the circuit.

15:30 So, 35 minutes to run of the first pre-season test of 2014. Just how revealing has the test been? How chronic are Red Bull and Renault's troubles? And just how excited should Mercedes be?

We'll be answering all such concerns over the next few days, including 10 things we have learned from Jerez, insight into what has been a dream test for Mercedes, and a reflection on the test in general from AUTOSPORT technical guru Gary Anderson.

15:36 Magnussen vaults Hamilton with a 1m30.806s - just the 16 thousandths of a second to choose between them then.

15:37 Alonso meanwhile is up to 113 laps for the day - 20 more than the entire field managed just 72 hours ago.

15:42 Massa goes purple in sector two, but AUTOSPORT's excitement is short-lived: he's around half a second slower than his current benchmark.

15:46 Nice that the weather is keeping things interesting here. Track temperature has just shot up, the dry line has spread and times continue to fall.

Felipe Massa once again leads proceedings, improving upon his own best to set a 1m28.521s.

15:47 As if to prove the point, Toro Rosso re-emerges for the final 15 minutes. Rookie Daniil Kvyat put in seven laps this morning, but hasn't run since.

15:48 Ah. Red flag - it couldn't be, could it?

15:48 Magnussen appears to have gone off in the McLaren.

15:48 And the Toro Rosso has stopped!

15:50 It looks like Magnussen has lost it exiting Turn 10, but the close proximity of the Toro Rosso indicates Kvyat may have been involved. No confirmation yet.

15:52 Will there be any more running? The McLaren looks like it has made it as far as the barrier.

15:57 Hamilton takes the Merc out into the pitlane and stops after just a few metres. Odd as we've still got a red flag. People are suggesting it might be an aero test, but that seems weird. There was, however, some flo-vis on the sidepod.

15:58 Just over two minutes left, so that's probably it as far as cars running on-track is concerned.

16:03 So, here's who has achieved what today:

1 Massa (Williams) 1m28.229s, 86 laps
2 Alonso (Ferrari) 1m29.145s, 115 laps
3 Juncadella (Force India) 1m29.457s, 81 laps
4 Magnussen (McLaren) 1m30.806s, 110 laps
5 Hamilton (Mercedes) 1m30.822s, 41 laps
6 Bianchi (Marussia) 1m32.222s, 25 laps
7 Sutil (Sauber) 1m36.571s, 69 laps
8 Rosberg (Mercedes) 1m36.951s 91 laps
9 Kobayashi (Caterham) 1m43.193s, 54 laps
10 Kvyat (Toro Rosso) 1m44.016s, 9 laps
11 Ricciardo (Red Bull) 1m45.374s, 7 laps

16:05 Well, the Toro Rosso and McLaren are being carried away and the teams have already started packing up.

16:07 There will be more details of exactly what happened there on AUTOSPORT later this afternoon.

Thank you for joining us on AUTOSPORT Live all week - in record numbers too.

The next Live action on the site will be Race Centre Live coverage of Rally Sweden on Thursday-Saturday next week, and the Formula 1 fraternity will no doubt have an eye on that event given Robert Kubica's stunning Monte Carlo performance.

AUTOSPORT F1 Live will be back for the second week of 2014 testing in Bahrain on February 19.

And keep an eye on the site over the weekend for more analysis features from this test.