Sebring 2: Bourdais on top

Bourdais strapped on a new set of tyres in the last hour of Thursday's afternoon session and stopped the unofficial clocks at 50.55 seconds. His team-mate, 2003 runner-up Bruno Junqueira did not run on the second day, but remained second overall as no other team has yet broken the 51-second barrier.

The rest of the field did pick up speed, however, with six of the seven cars present on Thursday moving into the 51-second bracket. Herdez Competition driver Mario Dominguez hit 51 seconds dead to go third on his first day at the test, while PKV Racing's Jimmy Vasser also made his first appearance, setting a best time of 51.7 seconds.

"It was my first day in the car since Australia last year so I just wanted to knock the rust off," said Vasser. "We weren't going for times, we just wanted to follow the testing plan. We ran over 100 laps and didn't have any mechanical trouble, so that's a plus."

Dominguez was pleased with his progress in the Herdez car. "We tried a lot of different things in the car today," he said. "We changed a lot of different combinations and were still able to be fast."

Rocketsports rookie Nelson Philippe caused a stir, getting quicker with each run. He lowered his time to 51.5 seconds by the end of day two. Team-mate Alex Tagliani ran in the low 51-second bracket.