A few years ago we used to say it was extremely bumpy and we would spend the weekend working on the suspension to absorb the bumps. But we saw in the last years that after the latest work, Interlagos is now no bumpier than most other tracks so that is no longer a feature. What we are left with is a very interesting lay-out which presents quite a challenge, with low, medium and high-speed corners as well as a long straight. This means you have to compromise in terms of downforce and drag level to get strong performance on the infield and give yourself a chance to pass at the end of the start-finish straight.
Will Interlagos suit the TF109?
We have always been quick in Brazil so we expect to be very competitive. In terms of aerodynamic efficiency Interlagos is close to the baseline configuration we run in the wind tunnel so our car is very well optimized to this kind of track. Last year we definitely had the pace to finish on the podium after Jarno qualified second with quite a lot of fuel on board. We had the race pace as well but it turned out to be a little bit difficult because of the rain. In the end we missed the podium and Timo did very well during those famous last laps on dry tyres when it was raining. Overall he gained a position and finished sixth but we were a little bit disappointed because we had the speed to be on the podium.
Will you take any special steps to help Kamui Kobayashi?
We saw already in Suzuka that Kamui is a very capable driver so we are confident he can meet this challenge, but of course we will be giving him additional support this weekend considering it will be his Grand Prix debut. He is very familiar with a Formula 1 car from all the testing he has done with us, where he has shown speed and consistency. However this weekend we will pay special attention to areas which are not his priority in testing; race pit stops, race starts and low-fuel qualifying for example. We will take full advantage of the practice sessions to familiarise him with every aspect of a Grand Prix weekend and we are sure he'll do a good job.
Now we are nearly at the end of the season, what is your assessment of the TF109?
This season we have been competitive on virtually every kind of track. We had a one-off drop in performance at Monaco but, as you can see from our second place in Singapore, we have understood the issue and recovered our low-speed performance. However, we have been inconsistent so at the end of the season we haven't scored all the points we should have considering our raw pace. Several times we have either qualified well and faced issues in the race or been extremely competitive in the race after a difficult qualifying. This has affected our final points total.
What were the strengths of the TF109?
All in all the TF109 has many strong points which is why it has been competitive on many different kinds of circuits this season. If I have to select specific areas, I would say aerodynamic efficiency is very good in the mid-range of downforce and we have good stability, particularly in terms of braking stability. This has meant the drivers are very confident in the car and it is relatively easy to drive.
Were there any weaknesses with the TF109?
Very early in on winter testing we found out the car was generally good so we had no specific problems to fix. Since then it has been all about development; just getting more performance and improving global aerodynamic efficiency. The only significant issue we had to address was Monaco as this weekend highlighted a lack of low-speed grip and downforce, which we have now solved.
How would you assess the development rate of the TF109?
For sure we have been pushing hard and the development rate has been significant. We started the season very competitively and we are ending the season at a similar level; this demonstrates we have certainly not been out-developed. We have put a lot of performance on the car throughout the season despite the testing ban which has really been a good effort from everyone. Obviously we have seen some changes to our relative competitiveness during the course of the season. The main reason is that the field is exceptionally tight so better or worse adaptation to a given track or slight preferences have resulted in unusually big changes to the order.
How important have tyres been as a performance factor this season?
This season's tyres have been a bit more difficult to manage than last year's. They are one step more peaky and more difficult to use, which is a characteristic of the slick compound. The slick uses its compound much better than the grooved tyres but as a consequence it makes the compound working range much smaller. These tyres have been more sensitive to ground temperature and warm up which created a situation where drivers were sometimes surprised from one outing to another by the level of grip. We have spent a lot of energy to find out early in each race weekend the exact thumbprint of each specification and what issues relate to them.
Has the movable front wing made a difference to performance?
It is something that, despite costing some weight, you would like to have for two reasons. Firstly it helps to tune the balance, and consequently performance, of the car during a given lap. When you have a balance difference between high and low speed sectors of a track you can tune the balance once per lap. This is particularly useful on a qualifying run or during the race when you can adjust to compensate for tyre degradation so for pure performance it is a big help. On top of that it makes the set-up process quicker. In the past when we were changing suspension stiffness or weight distribution, we had to anticipate the correct aero balance and, if you got it wrong, you had to pit to correct it. Now the driver tunes the aero balance himself on the out lap which really speeds up the set-up process.