‘McLaren yet to unlock car's potential’
McLaren have yet to unlock the potential of their new Formula One car with the start of the season looming, according to Jenson Button.
The 2009 world champion told Sky Sports television that there was plenty of work to be done at next week's final test in Barcelona after the Briton had less track time than he had hoped for on Thursday.
"It's been a very difficult few test days for me in terms of mileage," he said.
"It's been very tricky to understand where the car is: at times the car feels good, at other times it doesn't. And a lot of that is basically understanding the car that we have and making sure it's working as we expect it to be working.
"I really am looking forward to a good test next week in Barcelona because I don't feel we've been able to do enough to really understand the car and where we are with the car," Button added.
The season starts in Melbourne, Australia, on March 17.
Button had similar problems last year, even within the space of a race weekend when the car would look very quick in practice and then be strangely off the pace in qualifying.
The Briton, who won the opening race in Australia last year as well as the season finale in Brazil, said the new Pirelli tyres were another problem with high degradation after just a handful of laps.
"You have to throw a lot of new tyres at it and we don't have that many. So it's difficult to do set-up work and comparisons," Button said.
"I think we have a good base. If we can extract the best out of the car I think it is a good car. It's just that at the moment I don't think we're doing that."
Button was only seventh fastest on Thursday, completing 71 laps, a day after his new Mexican teammate Sergio Perez had been quickest.
Perez, who managed to make his tyres last longer than most with Sauber last season, was also disconcerted by how quickly the performance of the new Pirelli rubber wore off.
"It's extreme... and it's a big surprise," he said. "Normally we see in winter testing a lot of degradation but never this much."
"I definitely hope it changes because if we see this situation in Melbourne we are going to need something like seven or 10 stops to manage the race," added the youngster.
"Once you do one lap you start fighting degradation so it is difficult to learn anything from your car or from your balance."
Pirelli have introduced a new range of structures and compounds this season with the aim of producing more exciting racing and ensuring more pitstops.
The McLaren drivers were not the only ones expressing concern about the tyres.
Frenchman Romain Grosjean, at Lotus, said they would be a challenge.
"The tyres degrade a lot, I think in the first stint I came on to the radio on lap two saying 'The tyres are dead' but I had 66 laps to do so you try to do your best," he said after carrying out a race simulation.