ESPN rounds up all the reaction from up and down the paddock.
Mercedes
Nico Rosberg: "Every session is totally different because we have a limited amount of days and we're really pushing to the maximum in order to make the most of them. Today was a really valuable experience and we learned a lot of useful things for the season ahead. I'm optimistic for the start of the season and looking forward to my final pre-season runs in the car tomorrow."
Lewis Hamilton: "It's been really great splitting the days over testing because it feels like we're testing on eight days rather than just four with how it's worked out. The team has done a fantastic job with the car and we feel that we're probably in a stronger position than last year, especially after the mileage we've done. We've still not pushed the car to the limit though, to really find how to balance it on the knife edge on the timed lap, but personally I feel comfortable right now. It's kind of like building a pyramid, where the single-lap performance is the very pinnacle of the whole thing. At the moment we are building the base with our long running during testing - and the bigger the base, the higher you can ultimately go."
Ferrari
Kimi Raikkonen: "It was one of our best days of testing. We could run without a single stop, except for the red flags on track. Maybe we could have been faster on some laps, but in general the feeling was fine and we are more or less happy with the way things are going. Of course there's always room to improve and work to do. Like I said many times, I don't like guessing so there's no point in figuring out where we'll be in Melbourne. We will try our best as always. This morning I tried the Halo protection device and the difference to the usual driving was surprisingly small. The visibility is just a little bit limited at the front but I don't think this is the final version of the device, so it can be improved further."
Williams
Felipe Massa: Today has been a very positive day. We managed to do our programme without any problems, which included some long runs and also some short runs. We tried the soft and even ultrasoft tyres. Unfortunately I couldn't do my ultrasoft lap because we had some traffic, but overall it was a very good day and good to understand the car in a better way. I am definitely much happier this week compared to last week. We are almost ready for the first race, which is really when we will have a proper idea of where we are compared to the others, but today was a good day.
Rod Nelson, Chief Test & Support Engineer: It's been another productive day for us. We started off with some suspension and tyre tests this morning when the conditions were more stable, as usual here in Barcelona. Over the lunchbreak we did a grid process simulation, and then a first race stint straight after. We've also completed a qualifying simulation running on mediums, softs, and ultrasofts at the end. Sadly, Felipe couldn't set his potentially quickest time on the ultrasofts due to traffic, so he was actually quickest on a soft tyre. We also did some more system work and aero evaluations, so a bit of everything really. We'll spend a few days following the tests looking at all the data but I think we can be reasonably positive that we are up there at the sharp end. Exactly where we are we will only really know after the first few races of the season though. In terms of development, Felipe and Valtteri are both giving similar feedback. They are sensitive to different aspects of car performance, but they broadly agree with each other's comments, which really helps. They push each other on sportingly and technically, so are a good combination.
Red Bull
Danil Kvyat: "We almost got through our complete programme for the day, which was very useful and I feel we are ready for Melbourne. We had a couple of small issues today but nothing significant and it was a good final day. As for what we can expect in Melbourne, to be honest I have no idea! I'll go there with no expectations and I'll just do the maximum possible. These few days of testing have all been just about trying to make a better car, for myself and for the team, nothing else matters. We have done everything we can on our side and now we'll see what happens."
Guillaume Rocquelin, Head of Race Engineering: "Dany's final day was pretty much a mirror image of yesterday's running with Daniel. We began with a lot of pit stop practice, which again went very smoothly, so that kept us from proper running until around 11. After that we did some more aero work and short runs until lunch and then we completed a race simulation. We had a small niggle later in the afternoon that kept us in the garage for a little while, but overall it was as successful as yesterday, with Dany just 14 laps shy of Daniel's Wednesday total. In terms of performance there were some guys out there chasing a lap time today, which was interesting, but all through these tests we have just been focusing on getting well prepared for Australia, so we're still a little in the dark as to where we are in terms of performance, but we'll find out soon enough."
Force India
Nico Hulkenberg: "137 laps was not a bad way to finish my pre-season and today gave us a lot of indications about the tyres, including the new ultra-soft compound. They are grippier, a step forward from the super-soft, and we will need to learn how to make them work well. I feel we are as prepared as we could be, having gone through a few very productive days with no major interruptions. We went through our full test list again today and now we need to see where we pan out once we get to Melbourne. I see a lot of potential in the VJM09 and I know there is quite a lot in the pipeline, coming later in the season. It's very encouraging and I can't wait to get back to racing again."
Tom McCullough, Chief Race Engineer: "Once more, a positive day with lots of running and a full testing programme completed. It was Nico's final time in the VJM09 ahead of Melbourne so it was important to maximise our work with him and to give him as much time in the car as possible. The morning was quite busy: we continued the aero correlation work we have been carrying out during the first few days, running with test sensors fitted on the car in the first hour. The rest of the time before lunch was devoted to general set-up work, with shorter performance runs. After the break, we went on several long stints and, despite the interruption brought by a red flag, we were still able to gather a lot of useful data. We were also able to work with the softer end of the compound range and we had our first running on the new ultra-soft compound, so we will have plenty to analyse ahead of the final day tomorrow."
Renault
Jolyon Palmer: "I watched Kevin notch-up so many laps over the past few days that when my day didn't start to plan I was thinking 'why me?!' Once we sorted the gearbox problem it was great to complete a race simulation without issues. The car feels good and it was annoying to miss out on 100 laps for the day by a mere two laps! I think the team has made good progress with the car since we arrived here last week. I'm looking forward to getting some lower fuel runs as well as a full programme tomorrow."
Bob Bell, Chief Technical Officer: "We set out to have a good day with Jolyon after the frustrations he experienced losing time behind the wheel last week. It didn't go to plan in the morning with a gearbox issue which means he missed out on the lower fuel simulations we had planned. The crew in the garage did a great job to get the car back in action for the afternoon, enabling a full race distance to be completed, resulting in a strong recovery after a frustrating start."
Toro Rosso
Max Verstappen: "We had a very good test, both last week and this one, and today we've shown once again that the reliability of the car is very good, completing a further 159 laps. It's good to end my pre-season testing on a high and feeling as confident as I feel after these two weeks here in Barcelona. I'm now looking forward to the first race of the season! We've worked hard and made improvements, so it's time to get started!"
Phil Charles, Chief Engineer: "With Day 3 being Max's last day in the car before Melbourne, our program changed tack a little towards more specific race event preparation. To that end we completed more short running than we have been doing recently. In the morning we compared the softer compound types across short runs. This was very interesting for us as we have spent nearly all of our laps up to this point at T01 and T02 on Medium tyres. In retrospect, we will need to look carefully in the data to understand the different compounds. Our tyre group will be working hard with the chassis engineers to put the full picture together as we go forward from here. In the afternoon we concentrated on several race stint simulations. Again more useful information was gathered then.
"Overall we can certainly say that in the two winter tests we have put plenty of miles on Max (and the car!). This can only be a good thing and I hope that he goes away having learnt some more, and we will find ourselves in a good position to set the car up around him in Melbourne."
Sauber
Felipe Nasr: "It was another positive day in the new C35 car. We were able to accumulate good mileage on the car, doing a mix of short runs and a race simulation in the afternoon. That was really good, but we still have a lot of work to do. For me the next time in the car will be in Melbourne. I think, as far as the procedures are concerned, I have got myself prepared for the season opener."
McLaren
Fernando Alonso "I'm quite happy with our reliability so far. We've worked really hard over the winter and the answers we've got - especially on the power unit side - over the last few weeks are quite positive. In terms of performance, we are on standby at the moment, as it's difficult to read the times in winter testing as they are always changing. We'll wait for Australia: the same start time, everyone on the track, the same fuel loads and the same tyres for everybody, and then we'll get the answer. I think there's still a lot of work to do for us, but hopefully we are much closer than last year on the performance side.
"On the power unit side, there is still some potential to unlock in terms of performance, and also in the next steps that we need to take for the following engines that will come over the first few races. On the chassis side, there are still many things to be tested: some new concepts that we have on the car aerodynamically, and a new re-design on the back of the car that we need to keep studying and understanding how to use that area to maximise our potential.
"At the end of the day, I've had three days testing the car - not including the running we lost due to a mechanical issue. When you finish pre-season testing you always feel that there are still many things to test and work on in the car, and I feel the same now. I'm happy with the job we've done these past two weeks, but I'm sure during the first two or three races more potential will come, because we'll have had more track time."
Eric Boullier, racing director: "I'm very pleased once again that we've managed to surpass a century of laps on track today. So far, we have enjoyed good reliability in comparison to the same time last year, which has meant we've been able to spend a lot of time working on detailed evaluation and correlation of both our chassis and power unit.
"We have been regularly bringing new aerodynamic parts to the car this week, and today focussed heavily on correlating these with our simulation data and testing their compatibility with our chassis. Also new for this year is the suspension design, and we've been working hard to understand both its behaviour and how to exploit it to its full potential.
"Likewise, with the power unit, Honda has certainly made big gains in many areas - most notably with reliability until now, and an improvement in the deployment - but there is still a lot more than can be done before we can really maximise its performance.
"Today we ran both the Supersoft and Ultrasoft tyres for the first time in order to perform some race stint simulations and compare the data between the compounds, which was very useful and will help in determining our final set-up ahead of the first grand prix in Melbourne. We only have one more day of pre-season testing left - which as a team you never feel is enough - and we have a lot of work to do tomorrow to ensure we feel as prepared as we can before we fly to Australia."
Yusuke Hasegawa, Honda R&D head of F1 project: "We concentrated on maturing and setting our engine modes for race trim, and completed a full day's running with a stable power unit.
"On our last day of winter testing tomorrow, we plan to continue our evaluations, perform our final power unit data checks and preparations, and finalise our mode settings in order to ready ourselves for the season-opening race in Australia."
Manor
Pascal Wehrlein: "Given the choice, I'd rather drive fewer laps and be quick than more laps and be slow, so I can't be unhappy with where we ended up today. We lost quite a bit of track time because of some mechanical problems but I got a run on the Ultrasoft, my lap was good for 8th and we're in a good place with set-up. More laps, though nice to have, would only have confirmed that. Already the car feels a lot better than the one we started with last week, so it's quite exciting as there is a lot of development potential still ahead. There is a gap that we need to push hard to close but for the team it's much smaller than before and though everyone is tired after working so hard, we have some things to look forward to now. I feel at home with my new team so my thanks to them and I can't wait to be racing together in Melbourne in two weeks' time."
Dave Ryan, Racing Director: "We've had a few issues to deal with during the day and they took a while to get on top of but not a bad result from our 48 laps with Pascal. He did a great job with the limited running we gave him and though it's never wise to read too much into testing times, I think we can be reasonably happy with where we've ended up. Hopefully we can have a good run tomorrow to close out the programme but for Pascal that's his last lap until Melbourne. He's in good shape and has the confidence in the car so we're looking forward to seeing what he can do with it."
Haas
Romain Grosjean: "Not an easy day, not an easy week for us, so far. The first week of testing went very well. The second has been a bit tricky. We've had some challenges with the brake-by-wire system on the car, which has made things a bit complicated. However, we're working on it. At the end of the day, I had an off on turn nine. So it wasn't the best finish, but I think now we know where to look to get the car back to where it should be. Hopefully, tomorrow is a much better day."
Guenther Steiner, team principal: "It's been a challenging day. However, we managed to get some running in, so that was a positive. We had some issues with the brake-by-wire system while trying to develop it. We're still working on it and, therefore, it caused Romain to have a few offs, but this is what testing is about. We're here to learn and, hopefully, we'll be back out tomorrow to get some more laps in and understand the car better."