Defending SuperCars Champion Chaz Mostert makes his fifth career IMSA start — and first sprint race appearance — this weekend on the streets of Detroit, piloting the one-off No. 15 Vasser Sullivan Lexus RC F GT3 in the GTD Pro class.

Mostert last appeared in IMSA with Australian-based team 75 Express in the Rolex 24 at Daytona in January, where he earned a third-place GTD podium finish. Returning for his fifth IMSA start overall, the Australian said he is honored to once again compete in the series.

“Yeah, I’m super honored to be representing Vasser Sullivan and obviously Lexus as well this weekend,” Mostert said. “I flew straight in from Australia from Round 5 of our Supercars Championship driving the Toyota there.

“It kind of all stemmed around actually at Daytona when I got to catch up with Andy at Lexus and Vasser Sullivan. He heard I might be interested in doing a race for the team, and Detroit might be an opportunity for that going just to a GTD Pro entry for this weekend.”

“So, honored to be in the 15 car this weekend. Aaron (Telitz), my teammate, he’s absolutely mental and I’ll try to keep up with him. Then in the No. 14, the other two boys (Jack Hawksworth & Ben Barnicoat) are just lightning quick too.

“So I don’t know why they got a bit of a slow skippy kangaroo teammate, but I’ll try my best to keep up with them.”

Entering Detroit, the Lexus marks yet another new GT3 platform for Mostert. Having previously driven GT3 machinery from BMW and Mercedes, the Aussie has quickly built a diverse sports car résumé across multiple manufacturers.

“I think the beautiful thing about GT3 is the cars are all just so good. High downforce, great ABS and traction control systems these days,” Mostert said. “Probably the biggest thing for me is I really love the drivability of the Lexus. It’s actually got a very similar engine that we’ve developed this year in the Supercar, so that side of things kind of feels pretty close.”

“But yeah, I think the hardest part for me is just from what I’m used to driving in Supercars with no ABS and with a locked spool. When you come into these cars, it’s just trying to adapt as quick as you can to try and get the most out of it.”

“For me, the car feels really good. It’s a really bumpy, little interesting track, but the car’s really handling it quite well.”

“And yeah, looking forward to seeing what we can do over the 100 minutes here. It is a unique track. It’s probably the most unique track that I’ve ever driven on in a GT3 car. Probably here and Macau in a certain way.”

“But this is probably a fair bit more slow-speed corners, which really require mechanical grip, and the Lexus is doing a really good job of that.”

Not only is Detroit a new car-and-track combination for Mostert, but the downtown street circuit itself presents an entirely new challenge. While several WeatherTech Championship drivers are still learning the circuit following its return to the calendar in 2024, Mostert’s Supercars background gives him added confidence heading into the weekend.

“Well, this is probably the most prep I’ve ever really done for any track or new track for me, especially because I was so lucky to come over and hang out with TRD and do a little bit of sim stuff as well,” Mostert said. “So yeah, the sim stuff’s pretty new to me for my career. In Australia we don’t really have the really top-level sims, so it’s more just about learning where the track goes.

“But this weekend’s probably the first time I’ve had a really good lead-in and some unique and new tools that I’m not used to using. So yeah, I’m just absolutely honored to have that opportunity with Toyota and Lexus.”

“But it’s still a street track though, and you’ve still got to try and fight those little mental demons of trying to get closer and closer to the wall and being more aggressive on the throttle on exit when the car kind of bounces out right next to there.”

“So, it’s a game of millimeters around a street circuit, and you just keep going further and further and further until the wall tells you there’s no more to be given.”

This weekend marks a one-off GTD Pro entry for Vasser Sullivan’s No. 15 Lexus. Normally competing as the No. 12 in the GTD class, the team is effectively doubling its chances at a class victory in Detroit.

Without the pressure of a full-season championship campaign, Mostert admitted the weekend has carried a much more relaxed atmosphere — while also bringing some personal significance.

“Yeah, I hope it makes us a little bit dangerous because you’re not thinking about multiple races,” Mostert said. “We’re just trying to do the best we can this weekend.”

“But it’s also super relaxing as well. The expectation to try and put a championship together can be a lot of pressure.”

“When you’ve just got a one-off race, the only pressure is just trying to send it as hard as you can this weekend and get the best result you can without thinking too far down the road.”

“So yeah, like I said, honored to be representing the 15 car this weekend. It’s actually kind of a cool story because this was the exact same go-kart number I had growing up. I don’t remember the last time I actually drove with number 15. I adopted 25 in Supercars, so it feels like a bit of a homecoming in a weird way.”

Teaming with Mostert this weekend is Aaron Telitz, who has balanced both IMSA and SRO America commitments throughout the 2026 season.

Mostert has shared cars with several accomplished drivers during his sports car career, including Will Power during his Rolex 24 debut. But the Aussie had nothing but praise for his Vasser Sullivan teammate, even jokingly creating a special club for the weekend.

“Well first of all, he’s a fellow dad, so we’ve nicknamed ourselves the Dad Club,” Mostert said. “So hopefully we can do it for all the dads out there this weekend.”

“But he’s super fast and he’s a full open book. He’s really helped me get in the groove as quick as I can with the car and trying to help me through data and all that kind of stuff. He’s the ultimate teammate and I’m very lucky to be racing alongside him this weekend.”

One former teammate Mostert also reflected on was Alex Zanardi. Zanardi, who tragically passed away at the age of 59 less than a month ago, left behind an inspiring legacy that continues to resonate throughout the motorsports world.

“Yeah, I was so lucky in 2019 to share the BMW M8 GTLM at Daytona,” Mostert said. “Just his presence at the racetrack was unbelievable. We talk about how great people are on track, but honestly I think there was probably no better role model for motorsport than Alex.”

“One of the standout stories for me was every signing session. His line would go past the time limit, but he would make sure he stayed until every single person got through the line. And it might even be double the amount of time scheduled. I think there’s only a special amount of race car drivers in the world that put fans above everything else, and that was just second nature to him. He really got a kick out of meeting people, and obviously people looked up to him so much.”

“So yeah, it was tragic seeing him go. He lived his life to the fullest. In the little time I got to spend with him around racing, he was just a super positive guy and super fast. And what he was able to do in that race car with those hand controls was just unbelievable. Super impressive.”

As for his expectations this weekend, Mostert said his primary focus is simply keeping pace while embracing the opportunity.

“It’s kind of hard. I’m not too sure. Every guy in GTD Pro is just a world-class sports car driver,” Mostert said. “First priority is just trying not to make myself look silly and trying to keep up with them in the first place. If anything goes better than that, we’ll take it.”

“But sports car racing and endurance racing — the race has got to choose you. We’ve got an amazing team behind us. We’ll give ourselves the best chance to have a fast car and hopefully me and Aaron can somehow get in the mix. But expectation-wise, I don’t know. I’m just super honored to be here.”

As for when fans may see Mostert back in a sports car, it may not happen again until 2027 — unless another unexpected opportunity appears.

“Unless there was like a late call-up or something, and I just had to try and work it out with the Supercars schedule, this might probably be my last sports car race of the year. So, we’ll see how we go.”

 

Image Courtesy to IMSA