By Glenn Freeman Wednesday, March 14th 2007, 11:18 GMT
Allan McNish kept his car at the top of the timesheets for the second day running at Sebring on Tuesday.
The 37-year-old went marginally faster than Tom Kristensen had managed on Monday, in the car that both will share with Dindo Capello this weekend.
McNish praised the work of the Audi engineers over the winter, as he beat his qualifying record from last year by more than half a second.
He said: "There's not one major thing that would make you say 'wow, that's really different, and that's a testament to Audi getting it right first time.
"Last year the car was quite raw, and it was hard to make adjustments when we were racing so much.
"But during the winter you have the time to do all of the things you wanted to do but couldn't during the season."
Frank Biela was more than a second slower than McNish in the sister Audi R10, which he will share with Emanuele Pirro and Marco Werner this weekend and again at Le Mans in June.
Helio Castroneves led a Porsche 1-2-3 in the LMP2 class, as he was closely followed by fellow Penske driver Sascha Maassen, with Dyson Racing's Guy Smith third in class.
The Corvette's were comfortably faster than their only rival in the GT1 class, with Jan Magnussen setting the fastest time in the car that he will share with Ron Fellows and Jonny o'Connell.
Rui Aguas was able to use his experience of the Ferrari 430 to go faster than the existing track record in GT2, despite having never raced at Sebring before.
