Audi struck the first blow on the official test day for the Petit Le Mans at Road Atlanta, with Allan McNish and Dindo Capello's #2 R15 TDI setting the pace by 0.169seco over Stephane Sarrazin and Franck Montagny's No. 08 Peugeot 908.
All three of the major LMP1 manufacturers had a car in the top three – Gil de Ferran, Simon Pagenaud and Scott Dixon taking third in the De Ferran Acura, 0.8sec off the pace.
The session took place in dry and sunny conditions after the heavy rain that had affected the private tests in the preceding days.
McNish, who set the benchmark 1m08.308s lap, was pleased to be back at a competitive event as Audi's limited racing program has meant he spent most of the year testing.
"It was nice to be in a session with other cars," he said. "The R15 TDI was pretty good. It's still not ideal with the circuit being so green after all the rain this past weekend. But we're somewhere in the ballpark.
"The configuration of the car is very much the same as Le Mans, and that wasn't much different from Sebring. But there is continual room for improvement."
Nicolas Minassian and Pedro Lamy put the second Peugeot fourth, with the No. 1 Audi of Lucas Luhr and Marco Werner fifth having lost running following a trip off the road by Luhr. Highcroft Acura completed the top six.
The Butch Leitzinger, Ben Devlin and Marino Franchitti Dyson Lola-Mazda was the fastest LMP2 car, although class champion Fernandez Racing did not participate in the session.
The two Rahal Letterman BMWs topped the competitive GT2 field, ahead of the No. 45 Flying Lizard Porsche, the No. 3 Corvette and the Risi Ferrari.
Pos Drivers Cl Car Time
1. Capello/McNish P1 Audi 1m08.308s
2. Sarrazin/Montagny P1 Peugeot 1m08.477s
3. de Ferran/Pagenaud/Dixon P1 Acura 1m09.137s
4. Minassian/Lamy P1 Peugeot 1m09.234s
5. Luhr/Werner P1 Audi 1m09.821s
6. Brabham/Sharp/D.Franchitti P1 Acura 1m10.127s
7. Panis/Lapierre/Dumas P1 ORECA 1m10.309s
8. Field/Field P1 Lola 1m10.620s
9. Leitzinger/Franchitti/Devlin P2 Lola-Mazda 1m11.624s
10. Drayson/Cocker/Bell P1 Creation 1m12.216s
11. Pickett/Graf/Maassen P2 Porsche 1m12.549s
12. Dyson/Smith P2 Lola-Mazda 1m12.685s
13. Burgess/McMurry/Willman P1 Lola 1m14.013s
14. Van der Steur/Pecorari/Pecorari P2 Radical 1m16.220s
15. Hand/Auberlen/Priaulx GT2 BMW 1m21.574s
16. Muller/Milner/Muller GT2 BMW 1m21.798s
17. Bergmeister/Long/Lieb GT2 Porsche 1m21.838s
18. Magnussen/O'Connell/Garcia GT2 Corvette 1m22.056s
19. Melo/Kaffer/Salo GT2 Ferrari 1m22.275s
20. Law/van Overbeek/Neiman GT2 Porsche 1m22.302s
21. Sutherland/Drissi/Bell GT2 Riley Corvette 1m22.774s
22. Farnbacher/James GT2 Panoz 1m23.128s
23. Beretta/Gavin/Fassler GT2 Corvette 1m23.146s
24. Noda/Balbiani/von Moltke P1 Radical 1m23.530s
25. Sellers/Cicero GT2 Porsche 1m24.060s
26. Feinberg/Hall GT2 Dodge 1m24.143s
27. Murry/Robertson/Robertson GT2 Doran Ford 1m26.207s