The two Toyota GR010 HYBRIDs locked out the top two positions during Wednesday afternoon’s three-hour session, with Brendon Hartley setting the pace aboard the #8 car on a 3m27.742s.
That was almost two seconds up on the best time set in Sunday’s official test day.
It was the sister #7 Toyota that led the way for most of the session, as Jose Maria Lopez punched in a 3m28.290s early on, going a tenth faster than Loic Duval in the leading Peugeot 9X8.
That was then bettered by Kamui Kobayashi, who lowered the bar to a 3m27.875s when the session was resumed following a red flag prompted by a crash at Tertre Rouge involving the #777 D’station Racing Aston Martin Vantage and the #13 TDS Racing-run Tower Motorsports LMP2.
Casper Stevenson had already suffered an off in the D’station car and was stranded in the middle of the circuit when Steven Thomas slammed into the side of the stricken Aston, leaving both cars badly damaged. The session was resumed after a 35-minute delay.
Hartley made his improvement with 23 minutes left on the clock to make it a Toyota 1-2, 0.133s ahead of Kobayashi, before the session was stopped for a second time with four minutes to go.
That was caused by another crash at Tertre Rouge, this time for the solo Corvette C8.R of Nico Varrone.
Jumping to third late on prior to the stoppage was the best of the Cadillac V-Series.R LMDhs, the #2 Chip Ganassi Racing-run car of Earl Bamber, who managed to get within two tenths of Hartley’s benchmark with a 3m27.939s.
Next up were two Porsche 963s, with the #75 car of Felipe Nasr setting the fourth-fastest time ahead of Kevin Estre in the #6 car, both drivers coming within half a second of the pace.
Peugeot’s pair of 9X8 LMHs were sixth and seventh, Duval in the #94 car leading the #93 machine in which Mikkel Jensen set the best time prior to suffering a stoppage in the pitlane.
Ferrari, which had topped the test day with its new 499P LMH endured a low-key first practice session with Antonio Fuoco going eighth fastest in the #50 car, four places up on the sister #51 machine of Alessandro Pier Guidi.
Completing the top 10 were the #3 Cadillac of Sebastien Bourdais and the remaining works Porsche, the #5 car of Frederic Makowiecki.
In LMP2, an early lap of 3m34.579s from Pietro Fittipaldi in the #28 JOTA ORECA was enough to top the session by just three hundredths ahead of the #37 Cool Racing entry piloted by Malthe Jakobsen.
Prema’s #9 car recovered from an early incident in which it sustained rear wing damage to set the third-fastest time in the hands of Mirko Bortolotti.
Leading the way in GTE AM was the #55 GMB Motorsport Aston Martin Vantage GTE of factory driver Marco Sorensen with a best time of 3m55.020s.
Riccardo Pera was second-fastest in the #86 GR Racing Porsche 911 RSR-19, three tenths behind, followed by Valentin Hasse-Clot in another Aston, the #72 TF Sport entry.
The Garage 56-entered Chevrolet Camaro ZR1 NASCAR Cup car was comfortably faster than the entire GTE Am field with a best time of 3m49.475 set by ex-Formula 1 champion Jenson Button.
Early in the session, Robin Frijns survived an off at Tertre Rouge aboard the #31 WRT Oreca, albeit making contact with the guard rail.
Other LMP2 runners to hit trouble included the #35 Alpine LMP2 car, as Oli Caldwell crashed at the first part of the Ford chicane, and the #34 Inter Europol Competition machine, which broke down at the pitlane exit.
Also in the wars was the #66 JMW Motorsport Ferrari 488 GTE in which Louis Prette suffered a head-on collision with the barriers at the Ford chicane, with that car not reappearing for the rest of the session.
First qualifying for the Le Mans 24 Hours begins at 1900 local time, while second practice follows at 2200.
Results to follow