Kobayashi produced a 1min35.514sec lap in the #10 Cadillac DPi-V.R to beat the only Mazda RT24-P taking part, the #77 of Oliver Jarvis, by 0.180sec.
Loic Duval was a further 0.4sec down in the #5 JDC-Miller MotorSports Cadillac, with Matheus Leist fourth in class piloting the sister #85 Caddy.
In the overall times, however, Leist was separated from third fastest by a strong effort by Nicolas Lapierre in the LMP2 Tower Motorsports by Starworks Oreca. Harrison Newey’s best effort in the DragonSpeed entry was next best in class.
Neither of the Penske-run Acura ARX-05s took part in the session, and nor did the #55 Mazda or the #31 Action Express Racing Cadillac.
All seven GT Le Mans cars tested, with Earl Bamber heading teammate Matt Campbell by 0.178sec to lead a 1-2 for the Porsche 911 RSR-19s.
Daniel Serra’s top effort in Risi Competizione’s Ferrari 488 GTE took third, over four-tenths faster than Marcel Fassler in the #4 Corvette C8.R and DTM exile Bruno Spengler’s #25 BMW M8 GTE.
Alvaro Parente topped GT Daytona in the #57 Heinricher Racing with MSR Acura NSX GT3, but only 0.070sec ahead of the GRT Magnus Lamborghini Huracan of Andy Lally.
The GEAR Racing GRT Lambo of Rahel Frey was third, in front of the two Lexus RC F GT3s of AIM Vasser Sullivan Racing driven by Townsend Bell and Jack Hawksworth.