IMSA 2025 Sahlen’s Six Hours of The Glen

Get ready for Watkins Glen’s summer endurance classic as Porsche and BMW spearhead the German charge in GTP and GT classes. BoP tweaks, fresh entries and tight championship battles promise a six-hour contest of speed and strategy.

Why it matters

The Sahlen’s Six Hours of The Glen marks the halfway point of the 2025 IMSA WeatherTech season and the third round of the Michelin Endurance Cup. It’s the first time since Sebring in March that all classes reunite on track as LMP2 rejoins the GTP, GTD Pro and GTD fields. For teams and drivers fresh off the 24 Hours of Le Mans, Watkins Glen offers a fast, flowing 3.4-mile circuit, the “classic boot” layout, that demands both outright pace and endurance. This historic six-hour race is an IMSA cornerstone, and its midsummer date often brings heat and the threat of sudden thunderstorms (a 2024 cloudburst famously halted the race mid-way). In short, Watkins Glen is a stern test of speed, stamina and adaptability – a pivotal battle in the championships and a showcase for manufacturer prowess.

Entries and line-up

Porsche: Porsche arrives in strength, fielding the largest GTP contingent. Independent outfit Proton Competition joins the factory effort with a solo Porsche 963 (car #5) for Neel Jani, Nico Varrone and Nico Pino. Porsche Penske Motorsport runs its pair of works 963s, the #6 for Mathieu Jaminet and Matt Campbell, and the #7 for Felipe Nasr and Nick Tandy. Customer team JDC-Miller MotorSports adds another 963 to the mix: the yellow #85 shared by Tijmen van der Helm and Gianmaria Bruni. In GTD Pro, AO Racing campaigns its crowd-pleasing bright pink Porsche 911 GT3 R (“Rexy”), car #77 driven by young German Laurin Heinrich and Klaus Bachler. Porsche’s presence also extends to GTD, with Wright Motorsports entering the #120 Porsche 911 GT3 R for team boss Adam Adelson alongside Elliott Skeer and Australian up-and-comer Tom Sargent.

BMW: The Bavarian marque doubles down on its IMSA programmes. In GTP, BMW M Team RLL fields two BMW M Hybrid V8 prototypes, freshly fortified with a slight BoP power increase. The #24 will be driven by Philipp Eng and Dries Vanthoor, while the #25 features German ace Marco Wittmann alongside Sheldon van der Linde. GTD Pro sees Paul Miller Racing expanding to a two-car BMW M4 GT3 effort. The #1 BMW M4 GT3 is crewed by Madison Snow and Neil Verhagen (with Connor De Phillippi listed as the third driver), and Max Hesse and Dan Harper pilot its new sister car #48. In the GTD class, Turner Motorsport carries the BMW flag with its #96 Liqui-Moly M4 GT3 for Patrick Gallagher, Robby Foley and Jake Walker, a consistent trio eager to capitalise on the M4’s recent weight break in BoP.

Mercedes-AMG: No Mercedes are entered in the top prototype class, and none in GTD Pro – a reflection of the Stuttgart brand’s current focus away from factory IMSA efforts. However, the three-pointed star remains a force in GTD through customer teams. Winward Racing’s #57 Mercedes-AMG GT3 (Russell Ward/Philip Ellis/Indy Dontje) has been the class of the GTD field so far, coming off two wins in the last three races to lead the championship. They’re joined by Korthoff Motorsports’ #32 AMG for Seth Lucas, Kenton Koch and Daniel Morad and Lone Star Racing’s #80 AMG for Dan Knox, Wyatt Brichacek and Scott Andrews. All three Mercedes-AMG GT3s have shown competitive pace, with Winward emerging as a title favourite.

Audi: Audi is conspicuous by its absence. There are no Audi R8 LMS entries at Watkins Glen – indeed, no Audis on the IMSA grid at all. Audi Sport’s current priorities lie elsewhere (notably its Formula 1 project), and many of its customer teams have shifted to other championships. The Four Rings, therefore, watch from the sidelines this time. It’s a stark change for a marque that once thrived in American endurance racing, but one suspects Audi will not remain absent forever.

What to watch

• Porsche vs the rest: Porsche Penske opened the season on a four-race winning streak, conquering Daytona, Sebring, Long Beach and Laguna Seca. That run was finally broken in Detroit, where Acura’s Nick Yelloly and Renger van der Zande grabbed an upset win. Now, on a high-speed natural road course, can anyone stop the 963? Porsche’s GTP cars received no BoP breaks for Watkins Glen, so the team must rely on raw pace and consistency to stay ahead. All eyes will be on the #7 Porsche of Nasr/Tandy, which still leads the GTP championship despite finishing off the podium last time out.
• BoP boosts for BMW and Cadillac: IMSA’s Balance of Performance adjustments could shuffle the deck. Cadillac’s V-Series.R prototypes get a useful power increase for the Glen’s flat-out sections, and BMW’s M Hybrid V8s also enjoy a modest power bump. BMW Team RLL has frustratingly converted multiple pole positions into zero wins so far, so this could be their golden chance. If BMW’s reliability holds and tyre strategy clicks, Eng/Vanthoor and Wittmann/van der Linde have the speed to challenge for an overdue victory.
• Fresh contenders in GTP: The GTP grid expands to 13 entries, its largest all year. Two notable additions bolster the German ranks: Proton’s #5 Porsche (fresh from Le Mans) and the debut of Lamborghini’s SC63. The Proton Porsche trio of Jani/Varrone/Pino already gelled at Le Mans and will aim to impress in IMSA. Lamborghini’s programme is new and still finding its feet, but the star power of ex-F1 racers Romain Grosjean and Daniil Kvyat in the #63 could spring a surprise. Meanwhile, Acura and Cadillac bring full-season stalwarts (two cars each) eager to build on Detroit momentum, expect the Meyer Shank Acuras and Ganassi/AXR Cadillacs to fight tooth and nail with Porsche and BMW for every inch of asphalt.
• GTD Pro title tussle – Porsche vs Corvette (and more): GTD Pro is shaping up to be a thriller. AO Racing’s #77 Porsche 911 GT3 R (“Rexy”) duo Klaus Bachler and Laurin Heinrich lead the standings after back-to-back wins at Sebring and Laguna Seca. Only 11 points behind lurk Corvette Racing’s Antonio García/Alex Sims, the model of consistency with three podiums so far. Corvette’s new Z06 GT3.R hasn’t won yet, but Pratt Miller’s squad is knocking on the door of a breakthrough. Also in the hunt, just a few dozen points back, are the Detroit-winning Ford Mustang crew of Mike Rockenfeller and Sebastian Priaulx and the DragonSpeed Ferrari (Costa/Rigon) revitalised by a slight weight break. IMSA’s latest BoP tweaks hit some and helped others: the Corvettes must carry a bit more weight, whereas the BMW M4 GT3 was handed the most significant weight reduction. Paul Miller’s two BMWs could thus re-emerge as contenders after a difficult spring. Keep an eye on the #1 and #48 M4s if their form picks up with the lighter setup.
• GTD – Winward vs Lexus and German dark horses: The GTD class (full-pro/am GT3 cars) features 20 entries and a tightening title fight. Winward Racing’s #57 Mercedes-AMG (Ellis/Ward/Dontje) has two wins in the last three races and holds the points lead. But the bright yellow #12 Vasser Sullivan Lexus (Jack Hawksworth/Parker Thompson) has been relentlessly scoring podiums, three runner-up finishes on the trot, and is determined to claw back after a disastrous Daytona opener. These two outfits are favourites on Sunday, but far from alone. The #27 Heart of Racing Aston Martin (Stevenson/Robichon/Gamble) has twice finished on the podium in endurance races this year and could pounce if the leaders falter. And watch for two German dark horses: Turner Motorsport’s #96 BMW and Wright Motorsports’ #120 Porsche. Turner’s drivers, Gallagher/Foley (joined by rookie Jake Walker) have been quietly consistent with three top-six finishes so far. With the BMW receiving a helpful weight break, the blue-and-yellow M4 might find extra pace when it matters. Wright’s Porsche, meanwhile, has shown race-winning speed that bad luck has masked – Adelson and Skeer welcome hotshoe Tom Sargent back for the Glen, aiming to secure Porsche’s second GTD win of the season.
• Weather and strategy: A six-hour race invites the unexpected. Teams must manage traffic (four classes on track), execute flawless pitwork, and adapt on the fly. As last year proved, summer storms are not uncommon in upstate New York so a well-timed tyre call could swing the race. Fuel strategy will also be pivotal – six hours is long enough to require multiple pit cycles but short enough to make an unscheduled stop a problem. A caution at the wrong time can erase a lead or hand an advantage. In short, fortune will favour the prepared (and the bold) over 365 minutes of racing at the Glen.

RSR perspective

For Germany’s finest, Watkins Glen is both an opportunity and a stress test. Porsche is the benchmark – its factory team has set the pace all year – yet Detroit showed that the competition is catching up. A return to form is expected on a track where the 963 has historically been quick, but any slip could open the door for BMW, Cadillac or Acura to pounce. BMW, in particular, cannot afford another missed chance. The M Hybrid V8 has shown flashes of brilliance (multiple poles and podiums), and with a touch more power in hand, the wait for that first win may finally end on Sunday. In the GT ranks, the German marques carry high hopes: Porsche’s GTD Pro outfit and Mercedes-AMG’s leading GTD team both top their championships, underlining German strength in depth. Paul Miller’s BMW squad will be keen to turn their season around, armed with a more competitive BoP package.

And what of Audi? The absence of Audi machines on the grid speaks volumes about shifting priorities in sports car racing. While Audi’s focus has veered to other arenas, fans of the Four Rings can take solace in the fact that two ex-Audi GT aces – Christopher Mies and Frédéric Vervisch – are here, albeit driving Ford’s new Mustang GT3 programme in GTD Pro. Audi’s current hiatus from IMSA competition is likely temporary; a brand with such a rich endurance legacy will surely find its way back into the fray when the stars align.

In the meantime, the 2025 Six Hours of The Glen promises a classic endurance battle. Porsche and BMW will try to assert Teutonic dominance at the front, Mercedes-AMG’s customer teams will scrap for GT honours, and rivals from the US, Italy, Japan, and Britain will do everything to spoil the party. Endurance racing at the Glen is rarely predictable, and with championships on a knife-edge, expect every German team and driver to fight with typical spirit and precision. Whether a prototype duel at 200 mph through the Esses or a door-to-door GT brawl in the Boot, the stage is set for a six-hour showcase of performance and resilience.

How to follow

Fans can catch every session of the Six Hours live. Practice 1 takes place on Friday, 20 June, at 11:25–12:55 ET, with Practice 2 on Saturday at 9:00–10:30 ET. Qualifying is scheduled for Saturday at 14:20 ET (19:20 BST), split by class to decide the grid. On race day, Sahlen’s Six Hours of The Glen kicks off at 12:10 ET (17:10 BST) on Sunday, 22 June. US viewers can watch the race live on Peacock (NBC will also televise the opening hours from 12–3 pm ET). International audiences can stream the whole race and qualifying for free on IMSA.tv or IMSA’s official YouTube channel. No warm-up session is scheduled on Sunday morning, so teams will go straight into the race, adding more pressure to get the setup right by Saturday. Prepare for six hours of flat-out racing as Germany’s motorsport giants face off at the Glen.

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