De la Rosa surprised by 09-spec pace

De la Rosa has been driving the new McLaren MP4-24 at the Algarve circuit this week and believes that, although the car loses out in high-speed corners because of the reduction in downforce, the extra grip of the slick tyres in the low-speed corners balances it out.

"I'm surprised how little difference the slick tyres and the aero package have made," said de la Rosa. "The car has more grip at low speed, so we are definitely gaining time, but then losing a little bit in the high speed corners. I think that the laptimes will be very similar. What you lose on the high-speed corners you get back on the low-speed corners.

"The car has a little bit more grip at the front end generally and it is very responsive to steering. You have to put everything together - if you put these tyres onto last year's car, we would be three seconds a lap faster."

De la Rosa says the new slick tyres are the most significant change to the rules for 2009, and that the way they are managed by drivers could be one of the major challenges of the season.

"Tyres are the most important part because they are the only part that touches the asphalt," said de la Rosa. "KERS and the front-wing flap are only worth a few tenths, but these new slick tyres are the most important.

"We won't know how these new slicks will work until Australia because we are going to test in winter conditions. We don't know exactly how they will react at high track temperature or how much the degradation will be and how much they will be graining.

"This is the critical side. It has changed completely. It's not just that the tyre surface is different in that it's a slick. It's also the operating temperature of the compound that has changed a lot since last year."