ESPN rounds up all the reaction from up and down the paddock after the fourth day of testing in Barcelona.
Lewis Hamilton: "After Monday I was a bit sore - but I didn't break too much of a sweat today, so that's good. The reliability of the car this week has been just incredible. It feels strong, it feels solid, it just keeps going and going... I've never seen anything like it. The guys and girls at Brackley and Brixworth have done an unbelievable job. After two titles in a row, it would be so easy to lose focus.
"But it's clear that everyone is even more focused than before and have done an even better job of delivering an overall package with this car. In terms of today, the new front wing seems to be a step forward. It's small increments here and there - but that's what we're looking for. There's not much of a cliff with the tyres. They behave very similarly to last year's in that respect. It's been a gruelling week for the whole team - running between 150 and 190 laps every day. But I'd say it's probably been the best test we've ever had. Certainly the best I've ever seen."
Nico Rosberg: "It's been a great start. Reliability is looking very, very good and the car feels quick. It's great even to look at. You take a walk around it and there's some real innovation there. You can really see how far we've come as a team these past few years - it's very impressive. I can't wait to see what it can do when we get to qualifying in Melbourne. Pounding round on mediums all day isn't always so fun! Physically it's actually been ok. I knew it would be an intense couple of weeks so I prepared for it. Of course, there's a few bits that are sore - mostly from the seat as it's solid carbon. But overall I'm really pleased with how it's been. It's useful to have done so much mileage, as we found a few small problems that maybe we wouldn't have discovered with less track time. Nothing race ending - just small things - which could be very useful for Melbourne and beyond."
Kimi Raikkonen: "It was a normal test with different kind of tyres, but it is always different from what you see at the races. We have a new car here and there is always something to try, to test. So it is necessary to check everything. Testing time is painful, but it is better to do checks beforehand than having big problems during the Championship. I don't know if this is going to be a good car, no one can tell, but it seems to be a good car even if there are still many things to try out. We don't look at what the other teams do, we do our stuff and get ready. It's up to us to make sure we are in a good position. There is a good potential but we can still improve."
Felipe Massa: "I am not so happy with today - it was not really a useful day. The most important things was that we carried out our aerodynamic tests this morning, to understand the numbers and everything around the car. Unfortunately, we couldn't run much this afternoon. I had hoped to do more laps than I did."
Rod Nelson, Chief Test & Support Engineer: "Today was one of those days I'm afraid. We spent most of the morning doing aerodynamic correlation work which was pretty successful. We are getting through our programme day by day. Sadly, we had an issue with one of the car systems over lunchtime and that curtailed a lot of our running this afternoon which we had planned. We know what the issue is, we've got a solution, and now we look forward to next week."
Daniil Kvyat: said: "I had two quite good test days, even though we would like to do more laps. But we have two days left next week, so it will be important to extract the maximum out of that opportunity, to figure out where we can make steps forward. Obviously it's important to develop the car for the first race in Melbourne but even beyond that I think it will continue to improve as we understand the car more and more. We'll try to get as much done as possible next week, I'm looking forward to it."
Guillaume Rocquelin, head of race engineering, added: "We had a very good end to our first week of testing here in Barcelona. Overnight we found a solution to the niggle that affected us over the past two days and that enabled us to run pretty faultlessly today. It also meant that Dany was able to make up for the time lost yesterday. We focused on short runs, which is why the lap total is not that significant, as you obviously have to bring the car in more regularly and that delays things, but overall we're happy with the amount of work we got through today. In fact, I think we're satisfied with how the whole week went. Coming to the first test your main mission is to see whether you can run reliably, to find out if there are any issues and then to address those if you can. We've accomplished all those tasks this week and I think we're where we want to be. We have four more days of testing next week and they are going to be incredibly busy, so a small rest now and then full steam ahead again next week."
Alfonso Celis: "It's been another busy day with lots of aero and procedural work. Once again the car has shown great reliability and we managed to keep to the run plan without any significant issues. In the morning I was running mainly on the medium tyres and then moved to the softs in the afternoon. Each day in the car is a massive learning experience for me and I feel more comfortable with each run. I've also been able to get to know the engineers better this week, which is very important for the work I will do for the rest of the season."
Tom McCullough, chief race engineer: "Another useful day of testing as we continue to prepare Alfonso for the work he will do for us during some free practice sessions. For example, we made sure we worked through many of the car procedures that he will be expected to do later in the year. We combined this with aero correlation to make sure we captured all the necessary data to feed back to the factory. Alfonso continued to take a mature approach to the tests, improving with each run as he built up his experience in the VJM09. Overall we can feel happy with how things have gone this week. It has been a productive four days and we've made good progress with understanding the new car, which leaves us well placed to maximise the final four days of testing next week."
Kevin Magnussen: "I certainly have had a workout over the last couple of days with over 260 laps completed! It feels so good to be back in an F1 car and working through the programme and making strong progress. Our race simulation went well and I'm really gelling with the team; it's a real pleasure to be driving here and I can't wait to get back in the car on Tuesday."
Fred Vasseur, Racing Director: "This has been a productive first test for us. The initial R.S.16 planning meetings took place at the end of September last year so it's clear that everyone at Enstone and Viry-Châtillon has made a tremendous effort to produce it and facilitate the performance we've seen today and this week. Jolyon and Kevin have demonstrated themselves to be an accomplished and hungry pair of drivers. With the mileage accumulated over the last two days we have a good baseline. We have a lot of work yet to do, but it's a solid start to the season."
Max Verstappen: "Today was another good day, we managed to do a lot of laps, especially in the morning. We are understanding the car more and more and I think it all worked out well. The car is behaving well, so we can be happy. This first test has definitely given me confidence in the car. It was important to run as much as possible and we've certainly achieved this goal! I look forward to next week's test where we will continue to work as hard as this week."
James Key, technical director: "We can be pretty proud of the mileage we've achieved during this first test because we didn't know really what to expect, coming here with so many unknowns with the new power unit and a complete new car in the STR11. But I think the whole team has pulled together extremely well and made it possible to do four days of generally pretty productive testing. I think most of the things we wanted to achieve here we've done. Most importantly, we wanted to prove that the car worked as hoped with the new power unit installation and all the new complicated mechanical systems, and that appears to be the case, so we are very happy with that.
"The drivers have done a very good job. Carlos did 161 laps in one day, which is a huge amount of mileage, and I think he dealt with it extremely well. Max did 110 today, so in general we've had plenty of opportunity to prove reliability, which is critical with only two test sessions before the season start. Working with Ferrari has been extremely easy and straightforward, they've supported us very well. We've had some good cooperation with them over the past four days and I'd like to thank them in getting things prepared on time. We've ticked a lot of boxes for general car operation reliability, but we've only just started to learn what makes the car tick, so now we need to work much more on the performance side of the car, extract more out of that and bring some new updated parts next week. We're looking forward to that."
Felipe Nasr: "It was again a very intensive day. I collected a lot of mileage while driving the C34 for the last time. In the morning our programme was dedicated to tyre evaluation. I did many short runs on soft tyres. After the lunch break we mainly focused on set-up work and at the end of the session I was able to do a long run. Now I am very much looking forward to driving the new C35 next week."
Fernando Alonso: "Today was disappointing after starting the first couple of days of the test so positively. Still, it's good news that although the issue we had on the car meant we had to miss a lot of today's running, it's not a major problem and will be fixed in time for next week's test.
"Overall, we've managed a good number of laps during this test, which means we have a lot of data to analyse and learn from. Over the weekend we'll work hard to get everything prepared for next week, with the aim of getting as much time on track as possible."
Matt Morris, director of engineering: "Unfortunately, the coolant leak we experienced on the car today was in a tricky position, which meant it took longer than usual to locate and fix. It's always frustrating when a small issue hampers your running for much of a day, but thankfully it's relatively minor and we can now look to preparing the car for the second test on Tuesday. Testing is testing, and it gives us the opportunity to identify and work on reliability issues before we start the season.
"Over the course of the first four days in Barcelona we've done a good amount of running and already learned a lot about our package, which should stand us in good stead for next week. We're definitely ahead of where we were last year in terms of system checks and integration, so at the second test we'll be able to focus more on race simulations and setup, as well as characterising our package's performance." "We have a lot of data to go through over the weekend, and we look forward to getting back on track next Tuesday and continuing to get as much mileage under our belts as possible ahead of the first race in Australia."
Yusuke Hasegawa, Honda R&D Co Ltd Head of F1 Project & Executive Chief Engineer: "Our track time today was severely limited due to a coolant leak issue, which required more time than expected to find and rectify. To summarise our first four days of testing, we had a positive start, with confirmation of the improvement of the ERS deployment. However, the latter days revealed that there are areas of the power unit reliability that we need to work on to prepare for Australia onwards. In the second test next week, we are aiming to gauge the full performance of the c
Rio Haryanto: "It's been an important week for me and the team here in Barcelona and generally it's gone well. I've learned a lot about the new car and identified some areas for improvement, to make the second test even more positive for me. I did make a mistake this afternoon and the damage to the car could not be repaired quickly, so it's a shame we didn't complete our programme today. Generally though, we've achieved a lot of mileage and completed some good evaluation work. I've started to build a nice relationship with Manor Racing and also our Mercedes HPP and Williams teammates, so my thanks to everyone for helping me make a good start to my debut F1 season. I'm looking forward to making more progress next week."
Luca Furbatto, Chief Designer:"Overall, a positive first test with the new car. The main objective has been to check the installation of the Mercedes power unit and Williams transmission before progressing to basic set-up work. We haven't had any major issues out of the box and that level of reliability has enabled us achieve close to 300km of mileage each day - pretty much a race distance. We have also given our new drivers a good workout in terms of familiarising themselves with the car, albeit they ran to different programmes.
"Pascal's task was probably a little harder in that the car was literally brand new and we needed to find a good set-up from which to establish development direction. Rio focused on reliability runs and checks with different fuel levels. His feedback has been quite important because, of the two drivers, he is the one who has driven both the MR03 and the MRT05. This back to back insight suggests we've made some good improvements in all areas of the car. At this stage we aren't placing too much emphasis on relative lap times; some teams explored the full soft tyre spectrum here but next week's programme is where we'll start to look at more of the outright pace of the package. All in all we've made a good start but there's still a lot to do for Melbourne and into the early part of the season. We're positive about the first test, but already focusing on the second."
Esteban Gutierrez: "We had a productive day considering our circumstances. We completed a fairly good amount of laps which was the main program for today. Obviously we had some small issues in the morning and in the afternoon which interrupted the plan but it was all meant to be to solved and find out the reliability issues we can have in the car. This is why I think it was good, not ideal because obviously the ideal would be to complete the whole program, but the team did a very good job. The guys have been working very hard to put the car on track and we managed to do a fairly good amount of consecutive laps which will give us a lot of data to analyze and prepare for next week."
Guenther Steiner: "Well, we started off a little late this morning as we had some updates on the power unit which we had to get on. Once they were installed there was obviously a bit of downtime checking over everything to make sure we had a car we can start testing with properly. Then we got into the program. We've cycled the tires so we've been through the softs and the primes. At lunch we made some setup changes and put on a new floor. In the afternoon we were just going for reliability running. We did a few sets of 10-lap runs with the soft tires. We made some mechanical changes to the car as well, including ride height and a couple of roll-bar changes. We've been stopping on the marks for the driver and checking out the pit equipment. Hopefully, we can start doing some pit-stop practice in the next day or so. We achieved 79 laps. We've had a good day and the team's really starting to gel. It's all positive."