07:59 Welcome back to Jerez, for the final day of the first test.

There's been a bit of everything so far - a multitude of new drivers; McLaren, Lotus and then Ferrari on top; Mercedes hitting trouble on the first two days and then racking up 148 laps yesterday.

There's several more changes for today. Pedro de la Rosa arrives for Ferrari, while Jules Bianchi takes over the Force India. Oh, and this morning we have Max Chilton on Live. Get sending your questions to live@autosport.com.

08:02 Green flag, and Charles Pic gets us underway.

08:03 He's quickly followed by Kimi Raikkonen, Jean-Eric Vergne, Esteban Gutierrez and new arrival Jules Bianchi.

08:05 Raikkonen's first day in the E21 was enough to convince him the team has made made a step forward over the winter. Jonathan Noble was there to hear the Finn's view - read it here.

08:08 Lewis Hamilton is out on track for Mercedes.

08:11 And Hamilton is the first man to set a time, a 1m35.876s. Three laps now for the Briton - already roughly 25 per cent of his total from day two, when brake failure meant his day finished early and in the barriers.

08:15 After the initial rush - Pedro de la Rosa is the only man we haven't seen so far - Kimi Raikkonen is now our only man out on track.

08:16 Of course just as we type that he heads into the Lotus pit box right underneath the AUTOSPORT Live team.

08:21 Caterham on Twitter: "Roscoe belts in @Charles_Pic1 & we're off & running on Jerez day 4. Reports of glaciers freezing at turn 9 are tbc..."

In fairness, it is cold. One of the AUTOSPORT Live team even has a scarf on, which has prompted much debate about whether such items are permitted indoors.

08:22 Just over four degrees right now, although the track has jumped up to six within a matter of minutes due to the F1 effect. We've just coined that, but we're not sure if it works or not.

08:22 Given the conditions, Gutierrez's 1m20.797s is pretty impressive. He's only the second man to set a time today.

08:24 Williams on Twitter: "Pastor is also watching on- although his Venezuelan blood isn't used to to these temperatures... He doesn't like the cold! #Jerez #F1."

We can sympathise, even if we should be more used to it than Pastor is.

08:26 And an update from Force India: "The programme for @Jules_Bianchi involves aero sweeps to begin with. Later he will focus on tyre data collection combined with set-up tweaks."

08:30 Talking of Maldonado (08.24), he was our guest on Live yesterday, answering all manner of questions from our readers. Today is the turn of Marussia incumbent and F1 rookie Max Chilton.

He'll be on later in the morning, so get sending your questions to live@autosport.com.

08:31 Sebastian Vettel, on his second day in the RB9, moves up into second with a 1m21.547s.

08:33 Curious as to what Vettel thinks of the new car? He's had some pretty decent machines over the past few years, so how does it compare? Fear not - AUTOSPORT was there to hear what the German had to say after his first day. Read it here.

08:36 Vettel goes top now with a 1m20.551s. Track temperature continues to climb rapidly, even if the media centre is refusing to budge above four degrees.

08:39 Jonathan Noble spots a new sensor on the Force India sidepod. We were about to call him eagle-eyed, only the sensor is pretty big. Maybe perceptive works better.

08:40 AUTOSPORT Live's timing system is being kept busy this morning, with plenty of green and purple on the screens. Hamilton is the latest to improve as he dips into the 1m25s.

08:43 A few guesses from the office about which of the Live team is sporting an indoor scarf. We're remaining tight-lipped.

08:49 Sebastian Vettel goes purple in sectors one and three as he comes round in a 1m20.155s.

08:53 If you missed it, AUTOSPORT Live ran a very informal worst driver poll yesterday (read up on it here). After recommending himself, Taki Inoue eventually stormed to victory, much to his delight.

"Big celebration is going on. Now I'm a official worst F1 driver of last 20 years. I beat very strong contenders with big sweat!," he said on Twitter. "@LewisHamilton is enjoying his own first jet. I'm sweating to find the cheapest flight date in Easyjet."

08:53 And that will be the last mention of the worst drivers poll, we promise.

08:54 AUTOSPORT Live has been corrected by its own timing system. Vettel's time at 08.49 was in fact a 1m20.155s. We were out by 0.001s. Shoddy.

08:58 Pedro de la Rosa is still yet to appear for Ferrari, so we've had to use a shot from last year for now. He's the only man yet to go out. Kimi Raikkonen and Sergio Perez have both done four laps, but are yet to set a time.

09:03 Another two laps for Perez, but he's still yet to set a time.

09:04 No such bother for Gutierrez, who goes fastest with a 1m19.996s. Personal bests in sectors one and three and an overall best in the middle.

09:05 We have our first photographer vs marshal spat. To the delight of the Live team directly above it, LAT's Andrew Ferraro comes under fire from one, then another, of the pitlane marshals.

09:06 Ferraro is back in the building, so Edd Straw is off to investigate. We'll bring you the latest, because we're kind like that.

09:07 De la Rosa is out, and he's apparently keen to make sure everyone notices. He crawls around the first section, and is pretty much at walking pace between Turns 3 and 4.

09:08 Our first red flag of the day. We're not sure who it is, but the car does not look good. Very, very smoky from the rear.

09:09 Photographers scrambling now for the shot. It appears to be the F138 of de la Rosa, hence the earlier crawl.

09:10 The fire extinguishers are out and spraying. No fire as such, but there was a dense cloud of smoke coming from the rear of the F138.

09:10 The rescue vehicles and now low loader are at the scene. Speedy stuff.

09:13 De la Rosa is stopped between Turns 7 and 8, which is pretty much the exact spot AUTOSPORT passed Christian Horner and Adrian Newey on last night's run. We had to get that in there.

09:14 No oil reported on track. After a long inspection the Ferrari mechanics pull the covers over the car, and the low loader is moving into position.

09:15 Cheers from the Spanish crowd on the main straight grandstand as de la Rosa returns.

09:19 Ferrari on Twitter: "Difficult start of the day for De La Rosa: F138 stopped on track after the second installation lap."

09:26 The Ferrari is on its way back to the pitlane now. As we wait for the session to restart, here's a reminder that you can ask the man opposite any question you want as he'll be our guest on Live shortly. Keep sending them in to live@autosport.com.

09:26 A wealth of covers, shrouds and secrecy as the F138 is unloaded at the Ferrari pit box.

09:28 In other news, there's unconfirmed reports that the birds outside the media centre window have been attracted by the birdseed Edd Straw has been slowly consuming for the past two days.

09:29 And we're green again. Still a tumult of activity down at Ferrari.

09:30 Raikkonen, Vergne, Gutierrez, Hamilton, Pic and Bottas all out now.

09:31 Raikkonen incidentally had just bolted on new tyres and exhaust exits when de la Rosa brought about the red flag.

09:32 In a second straight instalment of 'odd but interesting', Valtteri Bottas has his dad watching on today. Must be a proud moment.

09:33 You can tell the track is warming up - there's a burst of green and purple pretty much everywhere on the timing screens.

09:33 Hamilton is our new pacesetter with a 1m19.733s, while Raikkonen (fastest in the first sector), Vergne and Bottas all improve.

09:35 Perez betters that with a 1m19.696s.

09:36 And we're red again. We have a car stopped just off line on the exit of the Senna chicane.

09:37 Glenn Freeman is convinced that it's the Sauber C32, and he's spot on. Unusual place to stop.

09:39 Another good response from the Jerez crew - rescue vehicles and low loader already on scene.

Our photo, of course, is of Gutierrez in full flow yesterday.

09:41 Efficient work from Sauber too. The covers are on and the car is being lowered onto the bed of the low loader.

09:44 In the break, how about a recount of how many laps everyone is on for the day? Interested? Mega.
Perez is on 10; Hamilton (17); Raikkonen (10); Gutierrez (26); Vettel (14); Vergne (13); Bottas (9); Pic (17); Bianchi (7); Razia (7); de la Rosa (2).

09:46 We have a low loader in the pitlane. Busy day for the rescue team so far. The Sauber garage is one of the closest to the pit entry, so we should be underway soon.

09:46 And just as we write that, we're green.

09:47 Sauber confirms the stoppage was a fuel run: "The team did a check of the fuel system and, as a result, @EstebanGtz ran out of fuel."

09:47 Given that it's the last day, we might see a few more of those in the coming hours.

09:51 Perez, Raikkonen, Bottas and Bianchi all out now.

09:54 Vettel joins proceedings in the RB9, just as Raikkonen goes fastest with a 1m19.157s.

09:56 Bianchi, Hamilton and Vergne all exit in quick succession and we have five cars out on track.

09:59 Vergne improves to a 1m19.361s. 15 laps for the Frenchman now, the same as Raikkonen and one less than Perez. They're our top three at present.

10:04 Jonathan Noble is on the spot but comes up trumps with a 100 per cent record in the 'new car name game'.

10:05 As he's doing that, Sebastian Vettel in the RB9 (that's an easy one) goes fastest with a 1m18.789s. Three tenths clear now.

10:07 Bottas snr will be pleased - Valtteri has just improved to a 1m20.683s, which puts him seventh.

10:09 Our Live chat with Max Chilton is coming up imminently. Team-mate Luiz Razia is currently 10th fastest, having completed seven laps so far today.

10:09 Gutierrez is still top of the laps chart with 26, although Hamilton and Vettel are only two shy of that mark.

10:11 Talking of Gutierrez, he's now the only man out on circuit.

10:13 And that quiet seems like a good time to have a quick snack - it might not be in the same league as truffles, but there's a lot to recommend about a good pain au chocolat.

10:18 An update from Ferrari, who earlier today suffered a fire just two laps into Pedro de la Rosa's first test outing (see 09.09):

"Work in progress to check conditions of the F138, it will take a while to hit the track again.."

10:20 Nico Rosberg managed 148 laps yesterday, and Lewis Hamilton is already on 27 for the day. His latest is also a personal best, a 1m19.575s set on the medium compound.

10:25 Vettel, Vergne and then Hamilton take turns improving the benchmark in the first sector speed trap. Hamilton comes round for the fifth lap of his stint, all of which have been in the 1m21s or lower.

10:29 Bottas shaves another few tenths of his best, which now stands at a 1m21.738s.

10:30 There's a sizeable gap behind the Finn - 3.7s to Pic (23 laps) and another 3.6s to Razia (10 laps). Bianchi (10 laps) is a further 4s down the road, with de la Rosa propping up the timesheets having not set a time.

10:32 Max Chilton's talk with AUTOSPORT Live is coming up imminently - the Marussia man is in the building.

10:37 Bianchi and Razia are both out now. The Frenchman improves twice in his first two laps, dropping down to a 1m22.263s.

10:39 Another improvement for Bianchi in the VJM06 - he's down to a 1m22.108s, just over 1.4s down on Bottas.

10:42 Four days in and the AUTOSPORT Live team is as close as ever - Edd Straw has just supplied us with Diet Coke. Great man. Vergne shaves three hundredths of a second off his best but stays third in the STR8.

10:48 You've been sending the questions in, so we'll start doing the asking (right after the carefully staged photo we took below). Liam Johnson has the honour of kicking off our Live chat with Max Chilton.

10:49 A lot of drivers have come & gone in F1. What is your target this season to make sure you keep your seat?

Max Chilton: "Your first year is vital in proving that you are worth being in F1. So you've got to spend the first year getting the best out of the car, show the team that you are really interested in the data and getting everything that you can out of one year. Being a part of F1, a lot is about if people like you and think that you are good at giving feedback. That's very important and that's what I'm going to work on really hard because I don't want to be in F1 for just one year, I want to be here for the rest of my career."

10:51 You come from a good racing family. Your brother went down the touring car route, so what took you down the single seater path?
Barry McManus, Ireland

Chilton: "My brother was always too big, he's built like a rugby player and he has always gone down the [non single-seater] car route. I've always been the tall skinny one, so single-seaters was the perfect route for me and I've always preferred F1 to touring cars. Most people in karting have set their eyes on F1. I was lucky that I got in a single-seater, I loved it and I was fast so worked my way up quite rapidly."

10:53 Because we're multi-taking fiends and all that, we're still keeping an eye out for all the latest on track. Vergne, Perez, Bianchi and Razia are all out. Perez has just set his fastest third sector time on his out lap.

10:54 That incidentally could be significant. A lot of drivers have been commenting on how Pirelli's tyres are switching on very quickly, but then degrading faster. The abrasive nature of Jerez has to be factored in, but generally speaking the consensus seems to be that Pirelli has achieved exactly what it wanted with its 2013 offerings.

10:55 Can you explain what it's like to be in F1 with just three words ?
Taner Selvi, Istanbul, Turkey

Chilton: Action-packed [AUTOSPORT rules that this is one word as it is hyphenated. Plus it sounds better than just 'action'].
Concentration.
Acceleration.

10:57 Max, are you confident that 2013 might be Marussia’s best year?
Philipp Ostaschewski, Munich, Germany

Chilton: "Yes, really confident. They have had a few tough years of being just short of where they wanted to be and this year, with all of the hard work they have put in over the winter, there are definitely some good signs in the car. We haven't done much running, but yesterday I could really see the benefits of the new car. They've got so much drive to beat certain teams that we can make that happen."

10:59 Perez gets closer to the 1m18s - he's just 0.198s shy of the breakthrough now.

11:00 It was only Vettel who had made the leap, but he has company now. In fact, he has someone ahead of him. Esteban Gutierrez goes top with a 1m18.669s.

11:00 The Mexican's lap included a new overall best in sector two, and personal bests either side for good measure.

11:01 What is your personal opinion about pay-drivers and what do you think should be done to make the financial situation of F1 better in general?
Anssi Tuovinen, Finland

Chilton: "Formula 1 has always been that way. You need financial backing to get into Formula 1. It's probably the world's most expensive sport and it helps for drivers to come with backers. That has never changed. At the moment, there has been a bit of a thing about it but I don't really know why because for years people have come with big sponsors. Now, the word sponsor has been changed to pay driver. I don't think it's a big issue. F1 without people bringing in sponsors would not be where it is now. It's the way it is and it's the way it has been for a long time."

11:04 We can confirm that Ferrari's earlier issue was a gearbox fault. The team is replacing it as we write.

11:06 Who is your Formula 1 or motorsport icon?
Kate Hewitt

Chilton: "Ayrton Senna because he was absolutely all out every lap, he gave it 100 per cent. I've also got the ultimate respect for Stirling Moss and Jackie Stewart. They took their life in their hands every lap. Back then, it was a lot higher risk and they deserve serious credit."

11:07 What is the biggest difference between the Marussia and other cars on the grid?
Rodrigo Scharnberg

Chilton: "I wouldn't say that there is a big difference. At the end of the day, there are usually tenths or small numbers of seconds between the teams. Last year, without the KERS, that was probably the biggest difference. Now we've got that, you'd be surprised at how little the differences are that make up the time."

11:08 Sebastian Vettel clearly didn't like being knocked off the top. A 1m18.565s reasserts his place at the head of the field.

11:08 Vettel found most of his gains there in the first sector, where he sets a new overall best.

11:09 As a British driver is there much pressure or a sense of unrealistic expectation in what you can achieve coming from the British press? Good luck!
James Clarke

Chilton: "I have my own goals and the team has its own goals. We are racing in our own championship where we are on the grid with the teams there. I try and ignore anything like that because everyone has their own goals that will change year on year depending on your car and where you are in your career. I have my set expectations and I want to exceed them!"

11:10 Raikkonen is also improving - he breaks into the 1m18s now with a string of green sectors.

11:12 We're going to have to wrap up our Live chat with Max Chilton, so we're into the final two questions. The first is from his photographer back in Formula 3, most commonly known as Beaver.

How are you coping without me?

Chilton: "I miss the jokes and the banter that we used to have. He used to look slightly worse for wear in the morning so that used to keep me quite entertained!"

11:16 And our final question for Max, which comes from Simon Strange, Kent.

Will we ever see you on Take Me Out like your brother?

Chilton: "100 per cent not! That's not my kind of thing! I'm settled with my girlfriend. He did that to get a bit of PR and he got a sponsor out of it so good on him for doing it. But that's not my thing. I'd find that highly awkward!"

11:20 And that's a wrap. A massive thanks to Max and Marussia!

11:22 Thanks to all those who sent questions in. We'll have more Live guests at the forthcoming Barcelona tests, so keep an eye out and get your questions in. Any wishes on who we should target?

11:23 All that's left to be said is good luck to Max, team-mate Razia and Marussia for the forthcoming season.

11:25 While we wrapped up, Sergio Perez becomes the fourth man to break into the 1m18s (he made it by 0.056s). He stays fourth behind Vettel, Gutierrez and Raikkonen.

11:25 Edd Straw has also been trying to elicit a wave from Lotus PR man Andy Stobart on the pitwall opposite our media centre base. Suggestions that this could be a new running feature on Live have been received warmly.

11:33 Vettel, Perez and Bianchi are our men on track at present.

11:33 Much life the off-season (sort of) Perez and Hamilton swap: the Briton heads out, the Mexican comes in. And yes, we're aware Perez wasn't at Mercedes last year...

11:35 With 30 minutes remaining of the morning, here's the current laps:

Vettel (51)
Gutierrez (52)
Raikkonen (25)
Perez (42)
Hamilton (52)
Vergne (37)
Bottas (35)
Bianchi (34)
Pic (38)
Razia (28)
De la Rosa (2)

11:36 Pic improves to a 1m21.919s, and he's now just over 1.4s down on Bottas in seventh.

11:38 Hamilton pops up in third with a 1m18.905s, set on mediums.

11:41 Caterham seem to be happy with their programme on the fourth day:

"Lunch in Jerez & @charles_pic1 has 38 laps on the board. We're well into the planned test program & now working on aero configurations."

11:44 Just as Luiz Razia improved in the Marussia, we're under reds again.

11:46 There's a lot of debris just on the outside of one of the turns which needs dealing with, and at first glance it looks like the kerb at Turn 5 is breaking up.

11:47 Yep, there's a big hole about one foot over from the kerb (on the rumble strip effectively). This might not be a quick fix...

11:48 Except we're green suddenly. The hole is still there though...

11:49 And we're red again. Thought that was unusual. It's not massively deep, but it looks about one foot round and is right on the edge of the kerb.

11:51 While we're waiting for a resolution, Brendan in Hong Kong has sent a question in for Edd Straw concerning Caterham's exhausts.

Hi, what's the news on the legality of the Caterham exhaust? Rumours abound that it breaches regs.

Edd Straw: "The first thing to note is that testing isn’t governed by the technical regulations (save for the necessity to pass the mandatory crash tests) so there is no problem in itself with Caterham running it at Jerez even if it has caught the eye of some rival teams.

"The vane in question sits in the exhaust channel and is there to turn the exhaust gases downwards. Many think it’s illegal, although if you accept the argument that it is outside of the imaginary cone at the exit of the exhaust where bodywork is prohibited, there is also an unpublished technical directive issued last year that could cause problems.

"Technical guru Craig Scarborough explains it in more detail here."

11:52 There are some Red Bull mechanics looking at the hole now. The issue is that any car travelling over it could pick up damage but could also damage the kerb and throw more debris onto the circuit. Like we said, it might not be a quick fix...

11:53 And here's a photo of the hole courtesy of ace snapper and sometime F1 journalist Jonathan Noble.

11:55 AUTOSPORT Live isn't infallible - the hole is actually between Turns 9 and 10. Apologies. We blame someone else.

11:57 It is pretty clear that they can't let the test resume until something is done to fix the hole.

11:59 There is now an awful lot of arm waving going on as track workers try and come up with a solution. Red Bull might have to call on the genius of Adrian Newey to work this one out.

12:01 Red Bull crew are now getting back in the safety vehicle and returning to the pits.

12:04 There is now a single track worker left standing near the hole. He is on the phone - either to his bosses or the local DIY store for some quick-drying cement

12:05 Unlike Barcelona, Jerez does not have an official lunchtime break - so track time is ticking away.

12:10 Still not much action down at Turn 9. Still a lonely track worker - who is wearing a leather jacket - wandering around.

12:11 Oh, help has arrived. Two men have turned up carrying what looks like some carpet

12:13 This is like rescue watch on an epic scale. They're now laying some fake kerbing (the black plastic version of a sleeping policeman) over the hole in a bid to fill it.

12:14 Incidentally, we're not sure why it seemed important that one of the track workers was in a leather jacket. But it did.

12:17 Black plastic version of a sleeping policeman not a clear enough description for you. How about a photo then. Once again it's from Jonathan Noble, our resident kerbing and masonry expert. You can follow him on Twitter here.

12:18 Oh, that's been abandoned now. Suggestions that all the repair work has managed to achieve is to make the hole bigger being ignored (possibly because they can't hear us) by the repair men.

12:20 There's nothing like staring at a hole repeatedly without moving for fixing it. We try that quite a lot when our car breaks. Poking around a bit also looks clever.

12:21 And we have cement! The media centre is genuinely (sort of. Mainly it's just AUTOSPORT Live) glued to the action. Can this work? How long will it take? Does the man who was standing and poking around a bit feel miffed that people are now doing something?

12:25 The good news is he's still there in his leather jacket, watching on and occasionally gesticulating. The bad news is that we can't see the state of the hole any more, and of course we no longer have cars out on track. Jonathan Noble makes the odd decision that the Lewis Hamilton press conference might be preferable to this and heads down to Mercedes.

Phil Waldron has emailed live@autosport.com politely reminding us there was no update on the Andrew Ferraro/pitlane police clash from 09.05 (see our terrible photo). We understand he was standing in slightly the wrong position, was unamused by the remonstrations of the officials but did still get what he needed. That's dedication for you.

12:30 Do you have a random question? Feel free to email live@autosport.com and we'll do our best to answer. Except if they fix this kerb and F1 testing resumes, although even then we'll do our best.

12:32 And if you have a serious question, all the better. When Edd Straw returns from his latest paddock trawl, he'll be thrilled to answer anything you might be curious about, be it illegal exhausts, complex front wings or how teams are adapting to the 2013 tyres.

12:33 Hole update: What looked like a big poking stick (we were excited) is actually a blower that is being used to dry the cement faster. Red Bull and Ferrari both have men inspecting the repair job.

12:40 David Freeman asks:

Will the tyres be better at Barcelona, or will they wear like this track since Pirelli have said the track is worse since last year?

We're going to have to apply the 'time will tell' platitude a little bit. Essentially, the teams are expecting Barcelona to be better, and it's reasonable to expect that. Jerez is the roughest surface F1 uses all year. You can read Pirelli's view here.

12:42 Oh, we're green again. We didn't see that coming, but then it is tricky to judge how dry cement in a small hole is.

12:45 Kudos to Matt Larkin, who asks a "Hole-y unrelated question" (nice).

How do the teams make sure that the various monitoring racks and sensors don't actually interfere with the things they are trying to test?

Teams ultimately can't compensate for it 100 per cent, because the sensors will have an aero effect - and sometimes parts on the rear of the car can have an impact on the front. But they will have an idea of what compromise the sensors will have, enabling to make allowances. Plus they will be looking for very specific data. They're able to work within the limitations.

12:49 Jules Bianchi has wasted no time since we went green. He's already broken into the 1m19s, with his first flying lap including new bests in all three sectors.

12:56 Edd Straw has made his way back to the media centre. After a brief catch-up on his own emails, he's diving in to see what you have been sending to live@autosport.com

12:57 While he does that, we have Gutierrez, Raikkonen, Vergne and Bianchi on track. None of them seem too concerned about trying to avoid 'the hole'.

12:58 We doubt there was much of a lunch break at Ferrari. Pedro de la Rosa is back out after his problems earlier on.

12:59 @eddstrawf1: "A great question from Amit Mandalia: "With Bernie confirming 19 races, which currently unused circuit would you like to have a 20th race at?"

13:00 Talking of de la Rosa, when he was walking from the Ferrari hospitality to the garage just now he tried his best Fernando Alonso 'march', which basically involves ignoring anyone who is excited to see him. Pedro couldn't pull it off though, stopping for a couple of photos with fans. He's just too nice...

13:00 @eddstrawf1: "Before we try and answer that, we're going to open that up to the readers! Tweet us using #autosportlive."

13:00 @eddstrawf1: "For the suggested 20th circuit, I reckon you could either suggest a realistic circuit (ie one that is active and somewhere near current F1 standards) or go with a more fanciful idea!"

13:01 The Ferrari returns to the pits. De la Rosa's lap count on his first day as a Ferrari driver is currently at three.

13:03 Having a Spaniard in the Ferrari - even if it's not the main man - has certainly helped the crowd figures at Jerez. The attendance has been smaller than we're used to all week, but the grandstands that are open have a few more people in them today.

13:04 Jules Bianchi could be winding up for another improvement. He's just started a flying lap on the soft tyres. Lewis Hamilton isn't far behind on track, running the mediums.

13:04 @eddstrawf1: "Early suggestions for the 20th circuit are Algarve from @itwasntandy and Imola from both @AlexBell179 and the man who asked the question @amit_mandalia."

13:05 Bianchi makes us look like we know what we're talking about by going fastest with a 1m18.175s. Thanks Jules.

13:06 @eddstrawf1: "From my AUTOSPORT colleagues, @EliGP suggests Jarama (clear Spanish bias there) and @mattnowtweets has gone for Cleveland (which would surely guarantee a first corner crash, as was the style in Champ Car). My ex-colleague @StevenEnglish inevitably suggests Croft (clear northern bias)."

13:08 After a slow lap, Bianchi follows up his timesheet-topping effort with a 1m19.1s

13:08 @eddstrawf1: "Former Dutch Grand Prix venue Zandvoort has been suggested by @koenvergeerF1. That would be spectacular, but not sure there would be much overtaking!"

13:08 De la Rosa heads out again. Ferrari is going to have to cram some work in this afternoon to give the Spaniard the information he needs before heading back to work in the simulator.

13:09 @eddstrawf1: "@richauty has called for Laguna Seca as the 20th F1 circuit and it would certainly be great to see grand prix cars through the corkscrew! We've also had a suggestion for a Daytona 'roval' circuit from @JournoRich."

13:10 It's more than an installation lap for de la Rosa this time, as he passes the pits. There really is little else going on of note at the moment, hence 'Pedro Watch'.

13:10 @eddstrawf1: "@f1zone has suggested the old Hockenheim. That would be an interesting one to allocate the DRS zones on!"

13:11 De la Rosa's first 'flying' lap (we use the term loosely) is a 1m25.713s.

13:12 @eddstrawf1: "@RobertMBarlow is keen on a revival of the Portuguese Grand Prix, last held in 1996. He suggests Estoril or Algarve."

13:13 @eddstrawf1: "My AUTOSPORT colleague @glenn_autosport has made a great call for the Norisring as the 20th circuit. That would be a unique spectacle."

13:17 De la Rosa is on his 10th lap of the day now, and he's trimmed some more time off of his best to get into the 1m23s.

13:19 Sergio Perez is giving chase to the Spaniard on track, but he's not making any inroads.

13:19 @eddstrawf1: "@gledhill56 has suggested Kyalami, last used in 1993. Would be good to see that on the full-length version. @stevvy1986 suggests Le Mans, which would be a great challenge! Incidentally, Le Mans did host a world championship grand prix in 1967, albeit on the short Bugatti circuit (it wasn't very popular)."

13:20 We've just had news that testing has been extended today. The session will finish at 1730 local time. That will give the teams back some of the time they lost to the stoppage for the hole in the track earlier.

13:26 Jules Bianchi is back out on track, but judging by his 1m25s laps, his focus has shifted after those quick runs earlier. Bianchi's role at the team is still not defined for this year, so he'll be hoping that 1m18.1s made a mark.

13:27 Jonathan Noble is back from spending some time at Mercedes. If he types any faster there'll be smoke coming from his keyboard.

13:28 @eddstrawf1: "@crashkidnorton and @toybota have suggested Bathurst. Now that would be something very special! An incredible track."

13:30 @eddstrawf1: "We have also had suggestions for Aintree, a London street circuit, the Nurburgring Norschleife and even a Scottish Grand Prix at Knockhill!"

13:32 De la Rosa is back out, and he's improved again. That puts him above Charles Pic's Caterham.

13:33 It's been a while since de la Rosa has had a car capable of out-performing Caterham and Marussia, of course.

13:34 Bianchi is still going round in the 1m25s. This one might be a little slower, as he just pulled over on the approach to Turn 1 to let Kimi Raikkonen through.

13:35 @eddstrawf1: "Our technical correspondent Gary Anderson has a great idea. A 20th F1 race on the Brands Hatch Indy circuit, with a reversed grid. 'That will sort the men from the boys' he says!"

13:35 Perhaps Bianchi wasn't being as generous as we thought. He pitted after letting Raikkonen through.

13:36 @eddstrawf1: "Also had suggestions for Long Beach, Anderstorp (which @F1John points out still has the same layout that it did back in its F1 days), Phillip Island, Pau, Reims and a road race around London's M25 orbital motorway!"

13:37 De la Rosa goes slowly out of the final corner, before stamping on the throttle just before the start/finish line. Whatever the experiment was there, we wonder if it was hampered when he skated past the apex to Turn 1.

13:39 Three cars on track (Gutierrez, de la Rosa, Pic), and they've all conspired to be within a corner or two of each other.

13:39 Meanwhile McLaren spots how empty the rest of the track is and sends Perez back out.

13:40 If you've only just joined us and you're wondering what on earth Edd Straw is doing naming all these random tracks, he's joining you in a discussion over where you would like to see a 20th grand prix held this year. As you can see from the suggestions (using #autosportlive on Twitter), there aren't many rules!

13:42 It's been a while since we updated the lap count for today, so here goes:

Bianchi 56
Vettel 56
Gutierrez 75
Hamilton 69
Raikkonen 41
Perez 58
Vergne 51
Bottas 39
De la Rosa 19
Pic 60
Razia 51

13:43 Razia is sat at the bottom of the timing screen for Marussia, but he's just improved on his best.

13:48 The 20th race discussion recently turned to legendary Australian track Bathurst. Here's a shot from 2011, when Jenson Button and V8 Supercars star Craig Lowndes took to the track in a 2008 McLaren.

13:49 @eddstrawf1: "Have had a flurry of suggestions from someone who wishes to remain anonymous, including Rouen, Pescara, Solitude and Tripoli! As a big fan of genuine, classic road courses, I fully endorse those as candidates for our fantasy 20th F1 race."

13:49 A glimpse of the McLaren pit board tells us Sergio Perez is going to be on track for another eight laps.

13:49 And on the subject of Bathurst car swaps, how about a video of the occasion?

13:52 Efficient work from the man working the McLaren pit board. Perez is only at Turn 4, and the board is already in position for his next pass of the start/finish.

13:53 To show just how hard it can be to read what's going on during testing, we currently have a McLaren, a Sauber and a Marussia all putting in laps within one second of each other.

13:56 @eddstrawf1: "@DeadManWoking has suggested France's Clermont-Ferrand. One F1 paddock regular (those who know him will be able to guess who) suggests Mallory Park! Also had calls for Road America, Indianapolis, Donington Park, Fuji, Adelaide, Okayama, Brno, Autopolis and Watkins Glen!"

14:01 @eddstrawf1: "Red Bull rising star Antonio Felix da Costa (remember the name, he will be in F1 soon) has joined the debate for the 20th F1 race...

@afelixdacosta: "#autosportlive back to Portugal, Portimao :)"

14:01 De la Rosa has put in several 1m21s laps on his latest run, but none of them have quite been quick enough to lower his best.

14:02 Kimi Raikkonen hasn't been as busy as some today (just 43 laps on the board), but he's just gone second fastest with a 1m18.326s.

14:03 The Finn's next lap is a 1m19.8s, as Jerez continues to punish the Pirelli tyres.

14:04 Another 1.1s lost on that lap for Raikkonen - he clocks a 1m20.9s.

14:05 Raikkonen pits after that short run. He was on the soft tyres, hence the big drop-off each lap.

14:06 We think Edd Straw is closing on a decision regarding the AUTOSPORT Live 20th grand prix...

14:07 @eddstraw: "Yet more suggestions for the 20th F1 circuit - Dijon (@crackers250), the Isle of Man TT course (@Work_in_F1), Montjuich Park (@OwainShawPl and @MadsBuhr), Dubai Autodrome (@mipp1), Crystal Palace (@willcampbell115) and Oulton Park (@legendnumber83)."

14:09 @eddstrawf1: "F1-star-in-waiting Antonio Felix da Costa also likes the idea of the old Spa (check out his latest Tweet @afelixdacosta)."

14:13 Lots of heavy running on medium and hard tyres out there at the moment. Vettel (on hards) is the only car lapping under 1m25s.

14:14 We've got Gutierrez, Hamilton and Pic doing 1m27s, and 1m28s for Razia.

14:16 @eddstraw: "Thanks for all the great suggestions for the 20th F1 circuit for the 2013 calendar. Some great calls, whether they were in the realistic or unrealistic category.

"Tempted as I am to go with one of the great road courses, I'm going to choose a venue that falls somewhere on the boundary of the possible and the impossible. Some of you have suggested it but it hasn't been mentioned here yet. My plan is to hold the Macau Grand Prix for F1 cars!

"Many practical reasons preventing it, not least the fact that F1 cars don't have enough lock to get around the hairpin - as Ralph Firman discovered when he did a demo run there in a Jordan - but the fantasy of a grand prix around one of the most challenging circuits in use is a great one."

14:19 Straw is now heading trackside to see what clues he can get about the 2013 cars (sorry Williams). And of course, when he returns, we'll make him write about it.

14:20 Vettel's current run has been a bit up and down. He's been fluctuating between 1m21s and 1m23s on the hard tyre.

14:22 As Pedro de la Rosa has an official non-race driver title at Ferrari, the timing screens have him down as car number 32. Jules Bianchi, who hopes to be promoted to race driver at Force India, has 15 rather than a test driver number. Does that mean something?

14:22 Almost certainly not.

14:23 Sauber is the first team to pass 100 laps for the day.

14:25 When Jonathan Noble spoke to Lewis Hamilton earlier, the 2008 world champion sounded pretty positive about his first proper running in the new Mercedes.

14:27 Following our mention of driver numbers at Force India, car 15 has been replaced by car 14. That means Paul di Resta has taken over from Bianchi.

14:29 With two hours of running left today (the finish has been moved back to 1730 local time), di Resta can make up for some of the time he lost yesterday due to an exhaust problem.

14:32 We've had a new best from de la Rosa, who now has 28 laps in the bag for Ferrari. His 1m20.316s puts him eighth.

14:35 Edd Straw has made it to trackside, and sends over some early observations: "Gutierrez is having to work hard in Turn 1, presumably his tyres have seen better days. He's struggling for stability in the turn-in phase and the rear is a bit difficult on the power. That's to be expected with high fuel and old tyres."

14:37 Straw also reports that de la Rosa has been working hard to get the front end of the Ferrari to do what he wants, but he appears to be making progress with it at Turn 1.

14:42 Sauber's recent Tweet about its programme for Gutierrez this afternoon tallies with our F1 Editor's observation about high fuel and old tyres: "A little less than two hours to the end @EstebanGtz is doing long runs in order to get used to the new tyres."

14:43 Lewis Hamilton joins the Mexican in today's 100 laps club.

14:45 Talking of laps completed, it's been a while since our last update. Here's how everyone is getting on:

Bianchi 56
Raikkonen 51
Vettel 74
Gutierrez 119
Hamilton 101
Perez 69
Vergne 68
De la Rosa 34
Bottas 53
Pic 77
Di Resta 14
Razia 75

14:54 Valtteri Bottas puts in an improvement in the 2012 Williams, which is enjoying its last track action today. The Finn jumps ahead of de la Rosa.

14:55 Bottas is on soft tyres, and follows up his 1m19.8s with a 1m21.1s.

14:56 Hamilton and Pic are the only other cars on track, and both are some way off those times at the moment.

14:57 Raikkonen leaves the pits and joins the track right behind Pic. He's straight on it too, giving the Caterham a very hard time rather than backing off to find space.

14:58 To the surprise of nobody, the Lotus comes round ahead of the Caterham.

14:59 Jenson Button might not be driving today, but he's in the paddock and checking up on McLaren:

"Another good day cycling as @SChecoPerez is in the MP4-28 today. Now back in the paddock catching up on the action."

15:00 Raikkonen really did mean business. His first flying lap is a 1m18.148s, taking him to the top of the order.

15:01 Raikkonen (on softs) follows up with a 1m19.8s.

15:02 Edd Straw could tell Raikkonen was pushing from trackside. He's just asked us how quick that first flying lap was.

15:02 The third lap from the Finn on this soft tyre run is a 1m21.0s.

15:04 All these Twitter pictures of F1 drivers cycling are not sitting well with our News Editor Glenn Freeman. He bought a new bike just before coming to Jerez, and picked up his first puncture after just 7 miles of riding it. Furious.

15:06 Edd Straw has moved from Turn 1 to the final sector of the lap. Here's what he made of that Raikkonen lap: "Mighty through the double right and excellent on the brakes into the chicane."

15:07 Straw has also checked in on the hole that caused that long stoppage earlier. He says it is starting to re-appear.

15:10 It appears that several of the drivers have taken the safe bet of simply not using the area just outside the exit kerb where the hole formed. But Sebastian Vettel is showing no such caution.

15:12 The German has come in, so it's just Perez's McLaren and di Resta's Force India on track now.

15:17 Raikkonen has returned to the track, this time on medium compound tyres. Here's some more of his early thoughts on the Lotus E21.

15:20 It's getting busy out there - eight cars on track now. Only Sauber, Caterham and Razia are in the pits.

15:21 Jean-Eric Vergne is one of those eight, and he's on soft tyres. His first sector is a personal best, so the Toro Rosso could be about to move up the order.

15:21 The man they call 'JEV' does improve, but not by much. He stays seventh.

15:22 We're heading into the final hour of the first test, and we'd like to hear what you've made of it all. Who looks good on the track, and who looks best off it (and do the vanity panels work)? Who is your dark horse, and which pairing are you most excited about? Tweet us at #autosportlive.

15:23 The track is busy by testing standards, but Paul di Resta and Pedro de la Rosa have both found enough space to do a slow-speed run past the pits.

15:25 Soft tyres doesn't always mean team's are going for a quick time. Bottas is out on the yellow-marked rubber at the moment and he's crossed the line with a 1m25s lap.

15:27 More trackside information from Edd Straw, who has moved to the fast Turn 8 left-hander: "The McLaren looks consistently good through here even when asking a fair bit of the rear. It's more planted mid-corner than the Mercedes, for example."

15:30 Lewis Hamilton now leads the lap count for today. He's got 122 in the bag, while Sauber's Esteban Gutierrez is in the garage on 120.

15:31 What have you made of Jerez then? Tweet us at #autosportlive.

@Andygf1: "Kimi is def my dark horse actually think lotus have been sandbagging and there's more pace to come."

@katmen: "I am sniffing very tight fights between Ferrari, Mercedes, McLaren, Lotus and Sauber."

@borboga: "I'm curious whether Caterham or Marussia could score a point in 2013 and I hope Red Bull will be strong again."

15:33 We're inside the final hour now. Remember, testing is finishing at 1730 local time today (instead of 1700 as it has been all week) after a long stoppage earlier to make repairs to the track.

15:35 Charles Pic goes out on soft tyres and finds 0.8s in the Caterham. His 1m21.105 keeps him 10th for the day.

15:38 More of your thoughts on the Jerez test. Keep them coming - tweet us at #autosportlive.

@dolphingroove: "Red Bull quickest. McLaren pretty close. Can't tell about my team, Lotus. Pretty slow times with Soft tyres. Heavy Fuel load?"

@gaittman: "All Lotus. Car looks great, air of calm from the team, Kimi and Romain on it. Title tilt from The Iceman."

15:40 Apologies for our lap counter going missing in the timing box - we'll be working on sorting that for the Barcelona tests. Here's another update on the current tallies for today:

Raikkonen 73
Bianchi 56
Vettel 86
Gutierrez 123
Hamilton 128
Perez 82
Vergne 72
Bottas 67
De la Rosa 39
Pic 98
Di Resta 29
Razia 75

15:41 At the moment, it's only the top two from that list on track. Mercedes will be pleased with the amount of work it has got done over the past two days after this test started so badly on Tuesday and Wednesday.

15:42 And a few more:


@Ndrose_84: "Doesn't the new Sauber paint job look like the HRT job from a few years back?"

@burnedsap: "Kimi and Lotus look good for championship."

@Mauin: "Roses are red, violets are blue, what I make of testing in Jerez? #F1 is back, baby!"

@DomSmithF1: "It's made my Uni week go a lot quicker! Great to have the cars back on track and overall it's been a good week for Jerez :)"

15:43 Edd Straw has made it all the way round to the Dry Sack hairpin - the furthest point from the pits. We're starting to have doubts about him doing all this on foot.

15:45 Straw gives his first feedback from Dry Sack: "The Mercedes is looking very neat and tidy now on this run, but clearly having to be very careful tyre wise. Lewis is very cautious on the throttle on exit."

15:49 As Straw feeds back his trackside views, you've been sending us some of your own:

@RapidScorpion: "Bianchi has majorly impressed me with 2nd fastest. Come on Force India, give this lad the drive!"

@GazUK: "Red Bull seam quick but with Massa's comments on JB's lap on day 1 they must have somthing in the bag."

@atisf1: "Field seems equal, no teams ahead of others, but Mercedes is my dark horse - are they reliable or massively vulnerable?"

@K7al_L3aft: "McLaren is the benchmark. From its long run times it looks so kind to the new rubber."

15:51 Our eagle-eyed (and possibly out of breath) F1 Editor has just seen a marshal pick something up from the side of the track on the backstraight.

15:52 Straw confirms our suspicions from earlier: he's now waiting for a media shuttle to bring him back to the pits.

15:53 Just Vettel and Bottas on track at the moment. The Williams has completed several laps on this soft tyre run. They're holding up in the 1m25s bracket at the moment.

15:56 A canny observation from our man trackside: "Bottas is using the DRS on the backstraight. Vettel isn't."

15:57 Those two have been joined on track by six more cars, as the clock ticks towards 30 minutes to go.

15:58 More soft tyre action for Vergne. The Frenchman jumps Hamilton and Perez to go fifth.

15:59 Vergne's lap included personal bests in all three sectors.

16:00 And a few more of your Jerez thoughts:

@DomSmithF1: "In my opinion, there's no doubt Lotus will be quick in Melbourne. But can they keep up in the development race this year?"

@RapidScorpion: "McLaren look to be the overall benchmark, but Lotus are close behind. Red Bull and Ferrari possibly sandbagging as usual."

@deadlycowpat95: I'm worried that it seems Lewis might be sinking to the front-midfield with Mercedes."

16:00 Vettel heads in, Razia and Perez head out.

16:04 Razia sets a new best in the final sector of his outlap. He's clearly timed his run well - three new bests take him to a 1m21.226s, comfortably faster than his previous best.

16:13 And a final few of your thoughts.

After trawling the paddock and talking to a litany of drivers, team bosses and engineers across the four days, Jonathan Noble will be compiling his own views on what we have learned from Jerez. Look out for it on AUTOSPORT.com tomorrow.

@kamacat86: "Toro Rosso looks like they may have made the biggest jump, though it's hard to tell from the first test."

@HamiltonManiacs: "Mercedes has immpressed me reliability-wise. Performance/speed will come."

@kamacat86: "Can't pick between McLaren, Ferrari, Red Bull and Lotus at this stage. Sauber, Force India, and Toro Rosso are in the mix too!"

16:17 Caterham on Twitter: "That's the 100 lap mark broken for @charles_pic1 who continues to circulate with just under 20 minutes left of day four."

16:24 Just over five minutes of the day, and the test, still to run.

Williams are gearing up for one last blast: "#BOTTAS back in and the team are preparing for what will be our final run of the week."

16:28 Two minutes to go, but the pitlane is as alert as ever. Pic sits at the pitlane exit a little bit too long and his car starts overheating. As the Caterham boys rush down, he finally tears onto the track.

16:29 And we're 90 seconds a way, all of which means AUTOSPORT Live's ballot of who will do a final out-of-fuel run could come to naught.

16:30 Perez cuts the chicane on his way back to the pits, where he performs a practice stop in his pit box.

16:31 The chequered flag waves and the first Formula 1 pre-season test of 2013 is officially over. Kimi Raikkonen has the honour of being fastest at the close, although Felipe Massa's day three benchmark remains the fastest of the whole test.

16:33 All that's left to say is a thank you to everyone who has been following us for the last four days. Keep checking AUTOSPORT.com for all the fallout from Jerez, including reaction from today.

We'll be back in less than two weeks for the first of the two Barcelona tests. Until then.