You had a strong race in China - Tony Fernandes called it the best Lotus has had to date - do you agree with that and is it a sign of things to come?
Yeah absolutely. It was a great race for us and in 18 months the team has done very well, I'm very pleased about the progress. I think it's been excellent work so far but we need to target higher. We should not be pleased with the result in China because we are targeting higher and we are working on the upgrades to do that. I think mechanically, especially at the rear, the car is very nice, it's just the efficiency of the aerodynamics that we need to push forward and that's something that we're working on to catch the cars ahead of us.

Mike Gascoyne said the next major upgrade is focusing on the rear of the car and should arrive in Spain, what do you think the potential of the car will be with the new parts?
On paper we know it's possible to gain one second in lap time. Whether it all turns out like that in reality is another matter. So far the correlation from our simulation to reality has been pretty good, so at the moment I have no reason to doubt that it will happen. If we can achieve that then it'll be a major step forward. We have plenty of capacity still at the front of the car so the more efficient downforce we can put to the rear, the more overall downforce we will have because we still have plenty of balance left at the front. So that's the most important thing and that's what Formula One is all about, creating efficient downforce.

How difficult is it to bring a big package like that to a grand prix and get it working straight away during Friday practice?
Like I said, I think so far the correlation between reality and simulation has been good, so I think it's pretty safe to expect it to work on the track. If it doesn't then it's something that we need to get going. That's the way it is in Formula One now because you can't go testing between races to see if it works or not, you've got to have the confidence in the updates. If it doesn't match our expectations then that's something that we need to work on, and for sure our facilities need to be up to that kind of standard so that we can put new parts on the car with 100% confidence and not worry.

What kind of circuits do you think the car suits and will it suit the ones coming up in Turkey and Spain?
I think it's worked well on all types of circuit. I don't think there is any kind of character of corner that it works better in than others. I think the temperature has been a main factor. In hot weather the car and the tyres are working better for us. The car is very easy on the tyres and if anything I hope for hot weather - a stinking hot Saturday and Sunday is better for us. But it's something that we are working on to make sure the car works well in colder conditions in the future. I think one of the key issues for that will be to put more stress through the tyres and that will come with the new aerodynamics.

So the problem goes further than just adapting your driving style?
We can work a little bit on the tyre and brake temperatures to get them working a little bit hotter, but it's pretty standard stuff. All the drivers are doing it so I doubt that you can find an advantage. You have to find an advantage from the machine itself.

From a personal perspective are you happier at Lotus than you were a couple of years ago at McLaren, despite being in a less competitive car?
I was happy at McLaren to be honest. I had a good time there, it's a hell of a team, but that time has passed now. I'm down with that, I'm all fine with that and I'm still very good friends with lots of people at McLaren, especially with Martin [Whitmarsh], Lewis [Hamilton] and all those guys - I keep in regular contact. It didn't work out but that's life and you've got to turn the page and try something else. I felt that rather than going somewhere that's halfway I had to go back to the beginning and go from the starting point again - I felt with a new team it was the best option for me. Every day as I see this team growing more and more it convinces me that that was the right choice. I'm very happy here so far. We've made some good progress and I'm enjoying being here.

And do you plan to stay at Team Lotus long into the future?
At the moment I've no need to change. I'm very happy working with Tony [Fernandes], Mike [Gascoyne] and everyone in the team. As long as I see the team progressing, why not? To be honest I feel I'm performing relatively better here than I was at any other point in my career, especially this year with some of the changes I have made to my training regime and the way I approach a race weekend - I think it's better. So no need to change.