Trulli: no quick fix for Toyota

The team endured a disastrous outing at the Sakhir track last year, with their car completely unable to use its tyres, and Trulli fears another repeat this time out.

"Very often we have some good races and some bad races," said Trulli, who finished seventh in Malaysia last weekend.

"This is often typical from this team because it looks like our car is very sensitive to different conditions and tracks. In Melbourne, it was okay and Malaysia was okay because it's a place where we've always gone well.

"But Bahrain hasn't always gone well for us. We were very bad in 2006. This is very difficult to explain - since we switched to Bridgestone we lost performance and something changed on our car."

Trulli believes that aerodynamics remain the team's biggest weakness and, although a major update is scheduled for the Spanish Grand Prix, he thinks that will only be the start of the improvement the team need to make.

"When you change the tyres, consequently the aerodynamic of the car changes," he said. "Look at Renault, they have lost out a lot while McLaren have gained a little bit. The only one who didn't change was Ferrari.

"Aerodynamically, that is the first thing, and everything else is related. We need to improve our aerodynamics. It's happening slowly - I wish we could do it in a quicker way. But it takes time to investigate, develop and design the parts.

"We are expecting a big aero update for Barcelona. I hope that from that time on we can improve our performance. For sure, our improvements will not let us win races - we are still very far from the top."