Russian Formula One driver Vitaly Petrov and his Caterham team spent practice for the German Grand Prix fighting the car’s tendency to understeer, he said Friday.

Understeer occurs when the car fails to turn enough in a corner, forcing the driver to apply extra braking before corners to avoid running off the track.

“Inside the car we tried a few setup changes to help dial out the understeer, and on the dry tires in the morning session we were definitely going in the right direction as the session ended,” Petrov said on the Caterham website.

Much of the first session was affected by rain, and the entire second session was run in wet conditions, meaning that Petrov was forced to be cautious, he said.

“I'm pretty pleased with how today's gone. In conditions like we had in both sessions one of the main things is to make sure you don't make any mistakes.”

Caterham introduced a new aerodynamics package for the last race in Britain, where wet conditions made it difficult to judge the car’s potential.

The team have tweaked the updated parts for the German race, technical director Mark Smith said Friday.

Petrov was 18th-fastest in the drier first session, and 21st in the wet second session, while his teammate Heikki Kovalainen was 19th in the morning and 17th in the afternoon.