Duval ended up nailing a 3:22.583s lap around the La Sarthe circuit in the Audi R18 e-tron quattro. Earlier he had a heavy whack in the #2 machine he shares with Tom Kristensen and Allan McNish at Tertre Rouge.
The #3 Audi of Lucas di Grassi was second three seconds down on Duval's best with the #1 Audi of Andre Lotterer third.
Toyota, fielding a twin LMP1 attack of TS030 Hybrids, finished fourth with the #8 car piloted by Stephane Sarrazin. The fourth Audi of Marco Bonanomi split the Toyota entries in fifth with Japanese giant's #7 of Alex Wurz sixth.
In the lead-up to the marathon on June 22-23, the LMP2 field was headed by Olivier Pla in the OAK Racing Morgan-Nissan.
Aussie John Martin clocked the 13th best time to be fourth fastest among the LMP2 runners in the G-Drive Oreca-Nissan.
Two of Martin's compatriots Ryan Briscoe and Jason Bright, having their Le Mans debuts, were also in action in their respective classes.
Briscoe was 25th outright in the LMP2 Level 5 Motorsports HPD ARX 03B-Honda.
BJR V8 Supercars driver Bright saw the Star Motorsports Ferrari 458 Italia in the LM GTE AM class he is sharing go 55th outright after the test weekend.
Ex-F1 driver Karun Chandhok clocked the 22nd fastest overall time in the Murphy Prototypes Oreca-Nissan he is sharing with topline Kiwi driver Brendon Hartley who did not do any running.