Juan Pablo Montoya and Franck Montagny led the way on the opening day of testing at Valencia in Spain on Wednesday, but most attention was reserved for Jenson Button who was giving the BAR its first serious public run.
Following BAR's decision to decamp to Valencia after the launch of the BAR007 at Barcelona on Sunday, because of problems with the asphalt at the Circuit de Catalunya, Button had to spend 24 hours kicking his heels, before being unleashed this morning.
And after ending the day less than one second behind Montoya's 2004-spec McLaren, the Briton was upbeat about his first taste of the new car in anger - despite an engine blow-up.
"It has been very windy, more than usual, so the conditions were quite extreme," he told autosport.com. "However, we concentrated on short runs to get used to the car and everything has run well. I am feeling confident with the car."
Although the fact that teams are running with vastly different configurations on their cars has made judging the importance of testing times more difficult than normal this season, BAR will be encouraged by the fact that Button outpaced team-mate Takuma Sato, who was using the hybrid BAR and suffered a spin at one point.
Jacques Villeneuve was the only other drivers using a 2005 cars, and he ended the day just more than one hundredth of a second behind Button.
Leading times from Valencia testing, Day 1 (January 19, 2005)
1, Juan Pablo Montoya (McLaren), 1m11.336s, 97 laps
2, Franck Montagny (Renault), 1m11.418s, 118 laps
3, Jenson Button (BAR), 1m12.209s, 78 laps
4, Jacques Villeneuve (Sauber), 1m12.217s, 92 laps
5, Takuma Sato (BAR), 1m12.355s, 84 laps