Testing for the LMDh cars that will make up the GTP class of the IMSA WeatherTech SportsCar Championship from 2023 and also be included in the World Endurance Championship continues to gather momentum, with Acura putting the first miles on its ARX-06 and Cadillac getting deeper into development with a five-day test at Sebring last week.

Acura did an initial systems check at Paul Ricard Airport last week before moving on to track testing with Wayne Taylor Racing driver Ricky Taylor and Honda Performance Development (HPD) Performance Engineer and racing driver Matt McMurry. McMurry, the 2020 GTD champion for Meyer Shank Racing, led development work on several software control systems on the ARX-06. Overall, the test went well according to HPD president and technical director David Salters.

“Of course, it is still early days, but I would have to say we’re quite pleased with the results of both the initial shakedown runs last week at Paul Ricard, followed by two days this weekend, which ran into the night both on Saturday and Sunday,” said Salters.

“Everyone on our team from ORECA, HPD, the Wayne Taylor and Meyer Shank organizations, worked together extraordinarily well in preparing for and conducting these initial runs. Now the truly hard work begins.”

The ARX-06 is based on an ORECA chassis and powered by an HPD/Acura engine combined with the spec hybrid system that will be utilized on all LMDh cars. Acura hasn’t released details of the engine package, but a turbo V6 is likely. The still-disguised exterior styling was developed with the Acura Design Studio in Los Angeles, along with HPD. The car will be raced by existing Acura DPi teams Wayne Taylor Racing and Meyer Shank Racing with Curb Agajanian.

Cadillac had already done a reveal of its LMDh prototype as well an initial shakedown a couple of weeks ago, but testing got into full swing with five days at Sebring conducted by Chip Ganasssi Racing drivers Sebastien Bourdais, Renger van der Zande, Earl Bamber and Alex Lynn. The test was done in conjunction with Porsche, which got the jump on its competitors with its 963 that has already undergone thousands of miles of testing.

Precision Crafted Peformance.

Track testing of the @Acura ARX-06 continued over the weekend at Magny-Cours. Another massive team effort from everyone at HPD and @Oreca – Thank You!#AcuraMotorsports pic.twitter.com/lVC00ulh6X

— HPD-North American Motorsport (@HondaRacing_HPD) July 19, 2022

“Discovering the new Cadillac LMDh at Sebring was a very exciting experience,” said Bourdais, who has co-driven with van der Zande to three victories this season, including Cadillac’s most recent DPi victory at Canadian Tire Motorsports Park. “The car is not only beautiful but also a ton of fun to drive. It is still early days and we have not focused on the setup work, but the base is already very solid and I can’t wait to get behind the wheel again soon.”

Added van der Zande: “You can feel the energy in the team. Everybody is very motivated to make this successful.”

Chip Ganassi Racing and Action Express Racing will race the Dallara-based Cadillac Project GTP Hypercar in the GTP category next year, and CGR will be running two cars in WEC Hypercar as well. The debut for the GTP category will be the Rolex 24 at Daytona in January.

“It was a fantastic feeling, driving the car down in Sebring,” said Lynn, who co-drove with Bamber and Neel Jani to victory in the Twelve Hours of Sebring in March.

“We learned a lot over the course of the five-day test. The Cadillac V8 sounds incredible, and it pulls extremely well. Looking forward to learning some more, but it was quite fun to drive, and we’ve got nothing but terrific signs at this point.”

Cadillac Racing assistant program manager Kalvin Parker noted significant work by the team of engineers to build on the initial test and the on-site support of energy recovery system suppliers Bosch and Williams Advanced Engineering. The all-new Cadillac 5.5-liter DOHC V-8 engine developed by GM’s Performance and Racing propulsion team based in Pontiac, Michigan, is paired to the LMDh common hybrid system.

With the first successful track test under its belt, you’ll be hearing more of the 2023 Cadillac race car’s engine soon. Stay tuned. @FIAWEC @IMSA #CadillacRacing #BEICONIC pic.twitter.com/uLz33jF8cm

— Cadillac Performance (@CadillacVSeries) July 12, 2022

“As we’re growing this complex system, we were able to lean on their expertise as well as our team’s expertise,” he said. “Getting the full support of our suppliers was key in getting in good miles.”

The development of the LMDh cars with their common hybrid system has been a unique exercise in collaboration, highlighted by the fact that Porsche and Cadillac tested together at Sebring. As highlighted by RACER previously, the cooperation between manufacturers that will be competing against each other on track – in conjunction with hybrid system suppliers Bosch, Xtrac and Williams Advanced Engineering and supported by IMSA, the FIA and ACO – has been unprecedented. That, notes GM sports car program manager Laura Wontrop Klauser, will contribute to the overall success of the category.

“The collaboration between OEs on the spec hybrid system development has been incredible and has enabled a more efficient timeline for issue identification and resolution,” Klauser said. “It’s great to work closely with those we compete against because we all want to make sure the spec parts are good to go and we can race it out on the track.”

Acura, Cadillac and Porsche will be joined in on-track testing of LMDh equipment by BMW in the near future. Those four manufacturers are going to be the first to compete with LMDh cars in 2023, with Lamborghini joining a year later.