The 22 drivers have their say on the opening day of action in Korea where Lewis Hamilton topped both sessions.
McLaren
Jenson Button: "The circuit is always very tricky, particularly at the start of the weekend; I don't think it's used at any other time of the year so it's always very slippery in first practice.
"However, I think our afternoon session was a little more representative of our overall pace. We got some reasonable mileage under our belts and, even though I didn't get the best from the Supersoft tyre on my fastest lap, I think we've begun to understand the characteristics of each tyre pretty well.
"In terms of performance, I think we might be a little bit closer to the Lotuses than we've been for the last couple of races - but let's see what tomorrow brings.
"Also during FP2, my mechanics needed to effect a quick fix to a brake adjuster switch inside my cockpit - the lever was adjusting itself under braking, so we had to tape it still. It had a very minor impact on my running."
Sergio Perez: "We completed everything that was on our list for today - including getting some useful laps on high fuel, which was very important.
"We still have quite a lot of work to do to optimise the car's set-up when running the Prime on high fuel, and work to make the Option perform to its maximum on low fuel, so it's going to be a tricky balancing act - but we're looking forward to it.
"Overall, I think we're in a similar position to where we were at the last race in Singapore: if we can get into the points, it'll be a good result for us.
"The anticipated wet weather might help us out, too."
Lotus
Kimi Raikkonen: "Obviously it didn't help that I destroyed part of the car this morning; maybe I ran out of talent there! It didn't cause too much damage and the car was fine for the second practice, even if the guys had quite a hurry to fix it.
"They did a good job and we managed to complete everything we wanted today. The car feels quite strong - especially on the long runs - so that's good news for the race. On the short runs it wasn't exactly as I wanted, but we still have some time to make improvements there."
Romain Grosjean: "My first two runs this morning weren't perfect, so we decided to change a few things during the break but that didn't exactly go to plan either. Finding the right balance for a full lap here is quite tricky as the different sectors are quite unique from each other, but eventually we returned to a more conventional setup for a run on the option tyres and the car felt much better.
"This circuit is a bit more front limited which doesn't particularly help us, but hopefully the track evolution will bring it towards us a bit more tomorrow. Half a second to the leaders is a bit of a gap and they look pretty quick, so I think top five is a realistic target in qualifying, but of course we'll do our best to catch them."
Mercedes
Nico Rosberg: "The track is really great and the small changes that have been made this year are good improvements, especially the pit exit which is now much better. Generally it seems that we had a good day but Red Bull is always very hard to beat. We were quite close to them today and I hope this will continue the whole weekend.
"My only concern after the long runs was graining on the front tyres, which is something we need to work on tonight and watch out for. We have brought also some new bits and pieces to Korea which are working well and leaves me optimistic for a strong result this weekend."
Lewis Hamilton: "I was very happy with how the sessions went today and it's the first time I can remember that second practice has really gone well for me. We haven't changed anything but the day just went smoothly and all the processes with the team worked well. I love this track: it was clean from the start, it provides good racing on Sunday afternoon and it just gets harder and harder through the lap.
"You have the first sector which is good for overtaking, then you get more and more corners coming at you and those final two sectors are all about precision. You need a good downforce package, too, and the car is feeling good. We can still make improvements overnight, and I have some things I want to do with the set-up, but it's been a good start for us."
Sauber
Nico Hulkenberg: "We were quite happy with the car this morning and found a good rhythm. The session this afternoon was a bit compromised because of the traffic. I couldn't really get the first two runs together and, I think, there is still room for improvement on the option tyre. The car was performing quite well this morning, however, this afternoon it was a bit more difficult. We need to look into that now. I don't think we showed our best today, but I'm confident for the rest of the weekend."
Esteban Gutierrez: "It was a very productive day. We've been trying different things on the car in order to adapt to the track. It's quite a challenge, because you have to compromise somewhere as the first sector has a high-speed character, while in the second and third sectors you need quite a lot of downforce. The track itself is really nice, even better than I expected it to be. It's fun to drive and has everything - fast, slow and medium speed corners.
"The first practice this morning gave me enough time to learn the track, and during the second session I was able to focus on the set-up and the balance of the car. Looking forward to qualifying tomorrow there is still room for improvement on the set-up."
Force India
Adrian Sutil: "I really like this circuit and the conditions were ideal today for practice. We worked hard to find the ideal balance and in the morning there was more understeer, while in the afternoon there was more oversteer. So there is some work to do to this evening, but we seem to be in a good position for the weekend."
Paul Di Resta: "It was quite a successful session and right from the first run I felt in the groove with the car. The long run pace looks promising and our tyre wear seems comparable to our rivals, which is a good sign. The area we need to improve is our one-lap pace so we will work hard tonight and hopefully find some gains ahead of final practice."
James Calado: "A new track for me and it proved to be quite difficult to learn, especially the last sector, which is quite a challenge with some off-camber corners. The programme involved some high fuel running, which is the first time I've done that, and by the end of the session I was feeling very comfortable with the car. The degradation of the tyres was quite high, especially as the track was so green to begin with, but I'm pretty happy with how things went today."
Williams
Pastor Maldonado: "Our performance wasn't up to the level we hoped for today, but hopefully we can analyse the data tonight and improve for tomorrow. We seem to have made a step forward with the new front wing but we need to work on the car as a whole to look at all areas. As always we will do our best and try to get the maximum out of the car."
Valtteri Bottas: "We did quite a few tests with the car today, both mechanical and aerodynamic. We still have quite a bit of work to do with the car balance as we are struggling with the front end, particularly in the mid-corner. We need to work on that, but the positive thing is that we seem to have made a step forward with the new front wing we tested on Pastor's car, so I look forward to trying that myself."
Toro Rosso
Jean-Eric Vergne: "We had a problematic Friday, with the main difficulty having to do with the balance of the car. We are not too sure what is the cause of these problems, so it will be a long night to study the data to try and find a solution. Strangely, the car felt better in the morning session. We are not happy with where we are now, but I still believe the car can be much better here, so we just need to put everything together in the right way and try again tomorrow morning."
Daniel Ricciardo: "Unfortunately we were on the back foot right from the first session, because the pace wasn't there. We really thought we could cure it for the second session, but that wasn't actually the case. However, I still believe this is a track that should suit us, but we are leaving it to the last minute to be competitive tomorrow. It would have been nice to have a good Friday session, so now we just have to work hard to turn things around."
Caterham
Charles Pic: "FP1 was ok for me. The track was obviously very green to start off with, and one of the first things I noticed was how bumpy the new pitlane exit is, but in general the car felt pretty good from the first full run. To begin with there was a bit too much front end in the high speed corners, especially through turns seven and eight, but it felt good in the low speed turns.
"For the next run we changed the rear camber and took off a bit of front wing and it definitely felt a bit better in the high speed turns, but overall there was a drop in rear grip and there was more rear locking, especially in the first sector. For the final run we made a change ot the rear ride height and it felt like it had improved the overall stability, especially in the last sector.
"Between FP1 and FP2 we made quite a few changes to the car and on my first run the rear stability had improved a bit from the morning session, as had the aero blance. Against that the traction wasn't great and in the very low speed turns the car was a bit sharp, mainly on entry and mid-corner, so we changed the ride height and front toe for the first run on options.
"On the performance run the supersofts started going off before the end of the first lap. The car balance was ok until the degradation started but after that it was understeering everywhere so we'll have to look at how we manage that tonight. I switched back to the mediums for the first stint of the long run but had to cut that a bit short after flatspotting the tyres in a small off. The deg levels until that point had been pretty good and that gives us decent options for Sunday, if it's dry!"
Giedo van der Garde: "Overall I think that as a better Friday than we've had for a while. I drove FP1 here in Korea last year so the track wasn't new to me and that's obviously an advantage when every lap counts towards maximising performance in FP1 and FP2 and it paid off today, even though I know I didn't get everything out of my quickest lap on the supersofts in FP2.
"In the first session, initially the car balance wasn't great. I had a bit of oversteer on entry into the high and low speed corners and we had some traction issues that meant I couldn't really push so we changed front toe and dropped the front wing a bit for the third run. Grip levels were obviously improving fast but the changes had pushed the car from oversteer to understeer, particularly in the medium and high-speed corners so for the last FP1 run we added back some more front wing and dropped the rear ride height a bit and by the end of the session we'd made some positive progress.
"In FP2 we started with a car that felt a lot better. I was immediately able to push and even though it was a bit on the edge in the slow speed corners, but generally the changes we made over lunch had worked well - basically it meant I could point the car where I want it and carry speed through the corners. We went onto the supersofts for the second run and found we had a bit too much understeer - that didn't help me put a clean lap together and I made a mistake in the final sector so I know I can find more time tomorrow on the options.
"We followed the usual Friday plan and I stayed on options for the first long run. They held up well but I was blocked about 16 laps into the long run and had to slow down, letting the tyres cool. Instead of trying to bring them back up to temperature we boxed and I finished the session on a set of mediums which were also performing well right to the flag."
Marussia
Jules Bianchi: "Overall I'm happy with the start of my Korean Grand Prix weekend. Having sat out FP1 I just needed to make the best of FP2 and get through as much set-up and tyre evaluation as possible, which we did with 31 laps. A good beginning but we need to make progress from here."
Max Chilton: "I've enjoyed a pretty promising start to what is a new circuit for me. We started the day with a bit of an imbalance and we tried a few things to overcome that, some of which worked and some of which didn't help. At the end of the day though we seem to have found our feet a little more at this track and so I'm looking forward to seeing how we can move forward from here."
Rodolfo Gonzalez: "It has been good to get back in the car again after a reasonable spell out of the cockpit, but unfortunately I made a mistake, lost the front wing and damaged the nose. Thankfully the damage was confined to requiring a new nose-wing rather than creating any problems that would affect the run plan for the rest of the day. When I was back on track I was able to achieve some good data from our aero evaluations."
