Sebastien Buemi believes Toro Rosso is set to make a step forward with its latest upgrade package, but warned that it might take at least the Spanish Grand Prix weekend to get to grips with it.
STR's technical specification is now much closer to that of senior team Red Bull Racing, which has been among the pace-setters so far this season. However last year it took Toro Rosso several races to extract the maximum from Adrian Newey's new design when it was delivered to the Italian squad, and Buemi - who was ninth quickest in practice today - expects that to be the case again in 2009.
"The car in this new configuration definitely has more potential, but I think it will take more than one race weekend to get the most out of it," he said.
He had found it hard to judge the new parts in the morning, and was then hampered by an early brake problem in second practice.
"In the morning session, we had the first opportunity to assess the new aero components we have on the car for this weekend," Buemi said. "It is hard to say exactly how effective they are, as in the morning session the track is green and you don't know what fuel loads the others are using or what tires they are on. But the overall feeling is positive and we are going in the right direction.
"In the afternoon, I had a problem with the rear brake, which unfortunately happened right at the start of the second session, so I lost some track time, before the guys got me out again. It's not the best way to begin the weekend, but we will just have to deal with it.
"We will be looking very carefully at Bourdais' data as well as mine from the second session, then factor in how we think the circuit will improve for tomorrow, when hopefully I can do my best to catch up."