Derani’s #31 Action Express Racing Cadillac DPi-V.R lapped the bumpy 17-turn 3.74-mile course in 1min47.882sec, just over a quarter second faster than Bourdais in JDC-Miller’s #5 Mustang Sampling entry.
More interesting still was a 0.4sec margin over Helio Castroneves’ Acura Team Penske ARX-05 which was a further 0.3sec clear of the sister car of Juan Pablo Montoya.
Even the fastest Mazda, the car that dominated the second half of the Daytona round two weeks ago, was over a second off the pace in this second practice session at Sebring, and the two RT24-Ps were separated by the sole Wayne Taylor Racing entry and the second JDC-Miller car.
Gustavo Menezes in the DragonSpeed Oreca led LMP2, half a second up on Ryan Dalziel’s best for Tower Motorsport by Starworks, while PR1/Mathiasen Motorsports’ late addition Spencer Pigot was third.
A very late run saw Frederic Makowiecki usurp Porsche teammate Laurens Vanthoor for top spot in GT Le Mans by less than one-tenth of a second.
Oliver Gavin running them close to grab third in the #4 Corvette C8.R, ahead of Jordan Taylor in the sister car, with the BMW M8s in fifth and sixth.
Toni Vilander led GT Daytona for Scuderia Corsa, the Ferrari 488 GT3 lapping just under two-tenths quicker than Daytona winner Aaron Telitz in the AIM Vasser Sullivan Lexus RC F GT3.
Gar Robinson set the best time in the Riley Motorsports Mercedes-AMG GT3 to take third, a hair quicker than Spencer Pumpelly’s Team Hardpoint Audi R8 LMS.
Qualifying for the Cadillac Grand Prix begins at 1.55pm local (Eastern) time, with the race start set for 5.35pm.