RACE REPORT: 2025 IMSA Detroit Grand Prix

Acura Topples Porsche as BMW Falters

Detroit’s concrete canyons never promise an easy ride. The 2025 IMSA WeatherTech SportsCar Championship round on 31 May was no exception. After a run of Porsche wins, the Chevrolet Detroit SportsCar Classic was billed as a clash between Penske’s in-form 963s and the field, with BMW’s M Hybrid V8 quietly threatening. But by sunset, it was Acura’s turn to steal the show and shake up the championship.

What follows is not just another race recap. Detroit left Porsche and BMW with bruises; some visible, some just beneath the surface. The battle for supremacy among the German giants remains the season’s main theme, but in Motor City, that story took an unexpected twist.

Why Detroit Matters

Street races are IMSA’s answer to a street fight: no room to breathe, let alone overtake. The walls punish even the smallest mistake. This makes Detroit a wild card on the calendar. Teams chasing the championship cannot afford slip-ups, but neither can they win by playing safe.

For Porsche, a fifth win in a row would have hammered home their status as the team to beat, especially with Le Mans just around the corner. BMW needed a strong showing to stay in touch; their M Hybrid V8 showed flashes of brilliance but not yet the relentless consistency of its rivals. Acura and Cadillac, meanwhile, would not be written off at home.

Porsche: The Streak Ends with a Bang

Porsche Penske Motorsport came to Detroit on a high. The two factory 963s, the #6 and #7, started strong, with Nick Tandy and Felipe Nasr in the thick of the GTP battle from the green flag. Tandy put the #7 Porsche up front at lap 27 when Nick Yelloly’s Acura pitted, and Nasr kept the pressure on after the driver change.

It looked like business as usual for Porsche until a bruising final stint. On lap 71, as the race approached its climax, the #7 Porsche found itself embroiled in a decisive incident with the #10 Cadillac. The two cars tangled heading into turn one. Nasr was forced wide, the Porsche bouncing down to fourth.

“It was a tough one to swallow,” Nasr said afterwards, visibly frustrated. “We were leading, and I really thought we had it. The contact changed everything. I tried to hold my line, but there was just nowhere to go.” The incident was reviewed by race control, who opted for no further action, which left the Penske pit wall shaking their heads.

Meanwhile, the #6 Porsche, driven by Matt Campbell and Mathieu Jaminet, quietly picked its way through the chaos and finished third. It was a measured drive: Campbell handed over to Jaminet at the halfway mark, the pair choosing consistency over heroics. “Detroit is about keeping it clean,” Campbell remarked. “We didn’t quite have the pace for the win, but we stayed out of trouble and picked up a trophy.”

The third Porsche, the customer JDC-Miller 963, had a messy afternoon. Tijmen van der Helm and Gianmaria Bruni fell a lap behind after a pit lane speeding penalty and never recovered, eventually finishing 11th.

In numbers: The #6 Porsche 963 of Campbell and Jaminet took third place. The #7 car, after leading and setting the fastest lap (1:06.641), came home fourth after that late incident. The #85 customer 963 finished 11th, a lap down.

BMW: Speed without Reward

BMW Team RLL’s weekend followed a familiar script: strong promise, then penalties and missed opportunities. The #24 BMW M Hybrid V8, with Dries Vanthoor and Philipp Eng, delivered a clean, if unspectacular, run to fifth. “We took what Detroit gave us,” Vanthoor explained. “You have to finish here before you can think about a result.”

The #25 BMW, however, had the pace to challenge for the podium before mistakes intervened. Sheldon van der Linde ran solid early stints before handing over to Marco Wittmann, who was hit with a penalty for pit crew over the wall too soon. As if that wasn’t enough, Wittmann then received a post-race drive-through for overtaking under yellow, a harsh blow that dropped them to sixth.

Wittmann did not hide his frustration: “We were right there on pure pace. It feels like we keep tripping ourselves up. If we clean up the little things, we’re right in the mix.”

In GTD PRO, the #48 BMW M4 GT3 EVO of Max Hesse and Dan Harper finished seventh, hampered by a penalty after contact with the #65 Ford. The #1 BMW M4 GT3 EVO of Madison Snow and Neil Verhagen struggled through a race full of off-track moments and a pit lane speeding penalty, finishing eleventh.

So, BMW’s top result was fifth in GTP with Vanthoor and Eng, sixth for van der Linde and Wittmann (after penalties), seventh in GTD PRO for Hesse and Harper, and eleventh for Snow and Verhagen.

GTD PRO: No Joy for Porsche or BMW

The GTD PRO class provided its own theatre. The #77 Porsche 911 GT3 R of Laurin Heinrich and Klaus Bachler had the speed for a top three, but incidents with the #14 Lexus and then the #4 Corvette saw the car slapped with a drive-through. “I accept responsibility for the contact,” Heinrich admitted in the paddock. “It’s racing, but it hurt our day.”

Ford took class honours, celebrating on home ground, while the German squads were left ruing mistakes and missed chances.

Absent Rivals: Audi and Mercedes-AMG

Neither Audi nor Mercedes-AMG fielded top-class entries in Detroit this year. Their absence was felt, especially with Ford and Corvette capitalising on the reduced German challenge in GTD PRO. If you want to know where Audi and AMG focus their energy, look to GT World Challenge and the Nürburgring 24. This was strictly a Porsche-BMW affair.

The Race in Context: IMSA, Le Mans, and Beyond

Detroit’s result means the championship picture tightens. Porsche’s margin shrinks. BMW will be left pondering what could have been. Acura and Cadillac, with a win and podium respectively, are not just spoilers; they are title threats.

IMSA’s GTP class is a genuine all-star contest, not just a private Porsche benefit. If this result rattled Porsche, it may be just what the championship needs. Campbell summed it up: “One bad weekend isn’t the end of the world. We’ll regroup.”

And for BMW? were Eng insisted.

Key Moments

• Lap 27: Nick Tandy puts the #7 Porsche into the lead as Yelloly’s Acura pits.
• Lap 40: Felipe Nasr overtakes Filipe Albuquerque’s Acura to lead.
• Lap 71: Nasr and the #10 Cadillac collide; Porsche’s win streak unravels.
• Multiple penalties: BMW and Porsche were handed drive-throughs, changing the race's outcome.
• GTD PRO drama: Penalties for Heinrich (Porsche) and Hesse (BMW) spoil strong showings.

Analysis: The View from RSR

Detroit exposed the cracks as much as the strengths. Porsche remains the benchmark, but they are now the hunted, as well as the hunter. BMW cannot seem to get a break. As we look ahead to Watkins Glen and Le Mans, both will know there’s no room for error.

For those sitting on the fence, this is exactly what IMSA needs: unpredictability, a hint of friction, and plenty left to play for. As ever, Detroit delivered its verdict without mercy.

RACE RESULTS

What to Watch Next

• Can Porsche regain momentum before Le Mans, or is the tide turning?
• Will BMW finally translate pace into a win, or will penalties strike again?
• Does Acura’s win herald a shift in the GTP order, or was this just a one-off?
• Will any other German manufacturers re-join the fray as the season moves into summer?

Get the next inside story first: subscribe to The Rennsport Report for original analysis, driver interviews, and every twist from IMSA, WEC, and the world of German motorsport.