By Cadillac’s lofty standards, the first two-thirds of the 2025 IMSA WeatherTech SportsCar Championship season fell comfortably short of expectations.
The American marque, with an expanded three-car GTP effort, experienced its longest winless drought since returning to prototype racing in 2017, having to wait until the penultimate round on the Indianapolis Motor Speedway Road Course to see a V-Series.R on victory lane. Across the eight years prior, the latest that Cadillac had scored its first win of the season had been round three.
However, once the form arrived, it stuck. The #31 Whelen Cadillac V-Series.R of Jack Aitken, Earl Bamber and Frederik Vesti followed up Indianapolis with another win at Petit Le Mans, vaulting the Action Express Racing-run effort up to second in the teams’ championship in the process.
And thanks to this late-season momentum, Action Express and Cadillac enter 2026 amongst the favourites for GTP championship honours.
“I think the fundamentals were always good,” Aitken tells DSC about their 2025 campaign. “And that was kind of proven by that we didn’t fundamentally change anything going into the final few races, and then to win two races back-to-back after such a start was a bit bizarre, but very welcome.
“I think that the #31 crew in the pit lane, for example, is the best crew in pit lane. I’d back them against anybody in a short fuel situation, to put on a set of tyres and get me out ahead of the others. They are truly excellent on that side. However, we’ll always try and get better.
“There are always things that we can improve. And we were always doing those little checks on ourselves through the year, but just as we always have done and as Action Express have done through the years. [Team Manager] Gary Nelson has been quite hard on us in that sense, and that is the ethos of the team. We always want to do better.
“I think the inherent speed of the Whelen Cadillac was always good. I think our performance in pit lane was excellent at times. The other factors, I think we could always improve a bit on and we did towards the end of the year.”
One of the challenges Action Express faced in 2025 was a significant change in the driving department. Whilst Aitken was entering his second full season with the squad, Bamber was new to the team, with Vesti and fourth driver Felipe Drugovich both being GTP rookies.
24-year-old Vesti, who made the step up to GTP after a single-season of LMP2 racing, was one of the breakout stars of the campaign, as he excelled on his transition to the top category.
“He was quick from the off,” Aitken says of his newest teammate, who featured in Action Express’ line-up at six IMSA events and the 24 Hours of Le Mans last season.
“It was just learning some of the intricacies of IMSA as a championship. I think specifically, from his side, he was pretty open that he was building his confidence up in the traffic and learning where he could afford those risks and not and where he could put the car fighting wheel-to-wheel with these guys who are pretty ruthless, and seasoned pros when it comes to taking advantage of young rookies and beating them up a little bit.
“But he then really hit his stride in the last couple of races. He was pretty reliable all the way through that part of the year, which is fantastic. And this year he’s armed with a bit more circuit knowledge. There’s no reason why he’s not going to be right up there with the best if he wants to carry on in that same vein.”
Aitken, Bamber and Vesti are all returning to Action Express this year, in the same roles as 2025, offering the Whelen-backed outfit a degree of stability it often hasn’t experienced in recent seasons. The only change is in the fourth seat at Daytona, with the team welcoming NASCAR star Connor Zilisch for a one-off outing. For the Briton, keeping the core squad together is a welcome move.
“I think you always have to count yourself lucky if you’re working with people that you can genuinely call friends, it’s not the norm in any job,” Aitken reflects.
“I think that’s the case in a race car as well. Me, Earl and Fred all get on like a house on fire in different ways. We come from slightly different backgrounds, different places in our career, whatever, and it just works. It all kind of fits together like pieces of a puzzle, which is really nice.
“We have our roles. We’re happy in those roles. There’s no ego of arguing who should start the race or who should do qualifying, who should finish and who gets that set of tyres. We’ll stick up for each other when we need to, and take a hit when we need to as well. And I really enjoy that environment. It’s really what endurance racing is about, I think.”
One of last year’s major pre-season talking points was the ‘One Cadillac’ approach that the brand adopted, with the aim of finding additional performance through greater collaboration between its factory-supported teams across IMSA and FIA WEC competition.
For Action Express, this meant working closely with a pair of outfits who were both new to the V-Series.R: Wayne Taylor Racing in IMSA, and Hertz Team JOTA at the 24 Hours of Le Mans.
“It’s been a really nice ethos,” Aitken says. “I think a lot of manufacturers strive for that kind of programme, and it’s not something that’s easy to achieve. Everyone wants to be that top car or on the top step, but it’s worked really well and has brought a lot of benefit to all three teams.
“Whether it’s the engineering crews talking to each other and exchanging notes on test days, sending crew members out to tests that their car is not attending because they know that they can learn things or aid in some way. It’s been really, really positive.”
Aitken will be taking greater advantage of ‘One Cadillac’ in 2026, as he adds an FIA WEC assault with Cadillac Hertz Team Jota to his IMSA Sportscar Championship programme, in place of the retiring Jenson Button.
The 30-year-old is looking forward to taking on the full FIA WEC, apart from the IMSA-clashing 6 Hours of Imola, despite the championship being a “different beast” to what he’s become accustomed to in IMSA.
“You’ve got a far lower density of cars on the track, not as much traffic to deal with,” he explains.
“You don’t have those sprint style restarts, really. But what you do have is just unrelenting time trialling, pure pace, and management of the tyres, the fuel situation, you really have to be inch perfect on that stuff. It’s really unforgiving, and it just builds over the stints, that advantage or disadvantage.
“Whereas in IMSA things reset. You can have fuel races, but more often you have those gun fights at the end of the race where everything resets and it’s ‘right, here we go, let’s have a fight’. And it’s brilliant that you have those different styles of racing. I really enjoy both.”
Aitken will carry on his partnership with Bamber in Hypercar, with them joined in the #38 Cadillac by Sébastien Bourdais.
It will be Aitken’s first full season alongside the French veteran, although the pair have both been part of the Cadillac family for the past three years, with them previously sharing a car at the 2023 6 Hours of Spa.
“I’m sure I will love doing WEC and representing Cadillac on a double front and working with the same people even more, because I’m pretty lucky with the people that I work with.
“Seb, although I haven’t spent as much time with him, I have shared the car with him once or twice before, and I love the way that he works.
“I have wanted to work with JOTA for a long time. [JOTA co-founder] Sam Hignett will tell you that I’ve knocked on his door and run his phone probably more than a few times, but that’s because I know that they’re a quality outfit. And it helps that they’re British as well. They’re closer to home. So the fact that we’re finally doing something together under the Cadillac banner is just fantastic.”
The dual programme means that Aitken is the latest driver to compete in both GTP and Hypercar at the same time, something which teammate Bamber first did last year, and has become increasingly common across several manufacturers as the category continues to mature.
It comes at a critical time in the Cadillac programme, with the V-Series.R receiving a significant overhaul in the off-season, including a striking new rear wing.
“It will be nice getting double the drive time in the Cadillac,” Aitken says.
“I do feel pretty comfortable in it, but seeing how comfortable Earl was in the car last year, and the ease of which he got into a rhythm, maybe that’s just his natural talent coming through, because we know he’s not slow, but I think it was a big sort of advocate for the double programme style that we’re seeing a few other manufacturers do as well.
“Time in the car is never a bad thing. And it also allows a driver to come across, transplant himself into a new team and a slightly different culture and environment, and say, ‘this is great, but here are a few things that we can think about’.
“They might work through your style or our style as a team, or they might not, but it’s something different, and having a fresh set of eyes effectively on each programme is great. So we’re going to try and double that up. Obviously, it’s going to be hard work and a lot of travel, a lot of air miles, but I’m pretty chuffed that it’s all come together, and I’m excited to see what happens.”
Aitken’s 2026 season begins this weekend at the Roar Before The 24 at Daytona International Speedway, where he, Bamber, Vesti and Zilisch will make their final preparations for next weekend’s 24-hour classic.
Images © IMSA, dailysportscar.com
