Earl Bamber led the way in the three-hour period on Saturday afternoon aboard the solo Ganassi-run Cadillac Racing LMDh with a 1m48.429s.
The time for the Caddy V-Series.R set early in the session was enough to eclipse the best of the Toyota Le Mans Hypercars by just over a hundredth, Sebastien Buemi taking second spot on a 1m48.443s.
But Bamber’s time was still two tenths shy of the laps in the 1m48.2s bracket both Toyota GR010 HYBRIDs managed in the morning session.
Jose Maria Lopez took third position in the afternoon with a 1m48.553s, which was three tenths off the time with which he topped the classification in the morning.
Ferrari took fourth and fifth position with its pair of AF Corse-run 499P LMHs, though the two cars were a second off the pace.
Antonio Fuoco set a 1m49.402s to just edge out Antonio Giovinazzi, who ended up on 1m49.573s.
The two Porsche 963 LMDhs were sixth and seventh, Frederic Makowiecki’s 1m49.657s putting him three tenths up on Laurens Vanthoor in the second of the two Penske-run cars.
Peugeot was again off the pace in the Hypercar class in eighth and ninth positions, Nico Muller’s 1m51.035s in the fastest of the 9X8 LMHs leaving him 2.6s behind the Cadillac.
Mikkel Jensen took ninth with 1m51.767s after the car lost track time following an incident between Jean-Eric Vergne and the Vector Sport LMP2 ORECA driven by Ryan Cullen.
Glickenhaus and Vanwall again brought up the rear of 11-car Hypercar field, Olivier Pla’s 1m52.203s for Glickenhaus outpacing Esteban Guerrieri by seven tenths.
United stays on top in LMP2
Phil Hanson was again quickest in LMP2 for the United Autosports squad, the Briton knocking more than two tenths off his morning best aboard the #22 ORECA-Gibson 07 to get down to a 1m51.492s.
The next two cars in class were four and five hundredths behind: Daniil Kvyat was second for Prema with a 1m51.534s just ahead of WRT driver Louis Deletraz on 1m51.589s.
Michelle Gatting also followed up on her GTE Am time-topping performance in the morning by going quickest again aboard the Iron Dames Porsche 911 RSR.
The Dane posted a 1m59.201s aboard the Iron Lynx-run car to end up two tenths clear of Ulysse de Pauw in the fastest of the AF Corse Ferrari 488 GTE Evos.
The WEC Prologue resumes for the first of two more sessions at 09:00 local time on Sunday.
| Cla | Nº | Driver | Car / Engine | Time | Delay | Laps |
| 1 | 2 | Earl Bamber Alex Lynn R.Westbrook |
Cadillac | 1'48.429 | 58 | |
| 2 | 8 | Sébastien Buemi Brendon Hartley Ryo Hirakawa |
Toyota | 1'48.443 | 0.014 | 74 |
| 3 | 7 | Mike Conway Kamui Kobayashi José María López |
Toyota | 1'48.553 | 0.124 | 70 |
| 4 | 50 | Antonio Fuoco Miguel Molina Nicklas Nielsen |
Ferrari | 1'49.402 | 0.973 | 35 |
| 5 | 51 | A.P.Guidi James Calado A.Giovinazzi |
Ferrari | 1'49.573 | 1.144 | 55 |
| 6 | 5 | Dane Cameron M.Christensen F.Makowiecki |
Porsche | 1'49.657 | 1.228 | 41 |
| 7 | 6 | Kévin Estre André Lotterer Laurens Vanthoor |
Porsche | 1'49.987 | 1.558 | 40 |
| 8 | 94 | Loïc Duval Gustavo Menezes Nico Müller |
Peugeot | 1'51.035 | 2.606 | 40 |
| 9 | 22 | Frederick Lubin Phil Hanson F.Albuquerque |
ORECA/Gibson | 1'51.492 | 3.063 | 70 |
| 10 | 63 | Doriane Pin Mirko Bortolotti Daniil Kvyat |
ORECA/Gibson | 1'51.534 | 3.105 | 56 |
| 11 | 41 | Rui Andrade Robert Kubica Louis Delétraz |
ORECA/Gibson | 1'51.589 | 3.160 | 72 |
| 12 | 9 | Filip-Ioan Ugran Bent Viscaal A.Caldarelli |
ORECA/Gibson | 1'51.675 | 3.246 | 60 |
| 13 | 93 | Paul Di Resta Mikkel Jensen Jean-Éric Vergne |
Peugeot | 1'51.767 | 3.338 | 12 |
| 14 | 23 | Josh Pierson Tom Blomqvist Oliver Jarvis |
ORECA/Gibson | 1'51.966 | 3.537 | 64 |
| 15 | 48 | David Beckmann Yifei Ye Will Stevens |
ORECA/Gibson | 1'52.134 | 3.705 | 56 |
| 16 | 31 | Sean Gelael F.Habsburg Robin Frijns |
ORECA/Gibson | 1'52.148 | 3.719 | 61 |
| 17 | 708 | Romain Dumas Ryan Briscoe Olivier Pla |
Glickenhaus/Pipo | 1'52.203 | 3.774 | 46 |
| 18 | 36 | M.Vaxivière Julien Canal Charles Milesi |
ORECA/Gibson | 1'52.210 | 3.781 | 53 |
| 19 | 34 | J.Smiechowski Fabio Scherer Albert Costa |
ORECA/Gibson | 1'52.456 | 4.027 | 63 |
| 20 | 10 | Ryan Cullen Matthias Kaiser Gabriel Aubry |
ORECA/Gibson | 1'52.602 | 4.173 | 68 |
| 21 | 28 | David H.Hansson P.Fittipaldi Oliver Rasmussen |
ORECA/Gibson | 1'52.679 | 4.250 | 50 |
| 22 | 4 | Tom Dillmann E.Guerrieri J.Villeneuve |
Vanwall/Gibson | 1'52.987 | 4.558 | 53 |
| 23 | 35 | André Negrão Memo Rojas Olli Caldwell |
ORECA/Gibson | 1'53.149 | 4.720 | 68 |
| 24 | 85 | Sarah Bovy Michelle Gatting Rahel Frey |
Porsche | 1'59.201 | 10.772 | 49 |
| 25 | 21 | S.Costantini Simon Mann Ulysse De Pauw |
Ferrari | 1'59.462 | 11.033 | 72 |
| 26 | 77 | Christian Ried M.O.Pedersen Julien Andlauer |
Porsche | 1'59.494 | 11.065 | 58 |
| 27 | 54 | Thomas Flohr F.Castellacci Davide Rigon |
Ferrari | 1'59.567 | 11.138 | 59 |
| 28 | 57 | Takeshi Kimura Scott Huffaker Daniel Serra |
Ferrari | 1'59.567 | 11.138 | 69 |
| 29 | 60 | C.Schiavoni Matteo Cressoni A.Picariello |
Porsche | 1'59.577 | 11.148 | 65 |
| 30 | 83 | L.P.-Companc Lilou Wadoux Alessio Rovera |
Ferrari | 1'59.645 | 11.216 | 58 |
| 31 | 88 | Ryan Hardwick Z.Robichon Harry Tincknell |
Porsche | 1'59.713 | 11.284 | 61 |
| 32 | 33 | Ben Keating Nicolás Varrone Nicky Catsburg |
Chevrolet | 1'59.829 | 11.400 | 44 |
| 33 | 86 | Mike Wainwright Riccardo Pera Ben Barker |
Porsche | 2'00.250 | 11.821 | 58 |
| 34 | 56 | PJ Hyett Gunnar Jeannette Matteo Cairoli |
Porsche | 2'00.429 | 12.000 | 61 |
| 35 | 98 | Paul Dalla Lana Axcil Jefferies Nicki Thiim Thomas Merrill |
Aston Martin | 2'00.659 | 12.230 | 58 |
| 36 | 25 | Ahmad Al Harthy Michael Dinan Charlie Eastwood |
Aston Martin | 2'00.880 | 12.451 | 59 |
| 37 | 777 | Satoshi Hoshino Casper Stevenson Tomonobu Fujii |
Aston Martin | 2'01.114 | 12.685 | 64 |
