The IMSA SportsCar Championship heads to upstate New York this weekend for the Six Hours of the Glen, the sixth round of the season and the third leg of the Michelin Endurance Cup following the 24 Hours of Daytona and the 12 Hours of Sebring.
Watkins Glen International, one of North America’s most iconic circuits always delivers compelling storylines. Here are five to keep an eye on this weekend.
Can JDC-Miller keep the upper hand over Porsche Penske?
JDC-Miller MotorSports pulled off one of the biggest upsets of the GTP era by winning at Laguna Seca. Not only did the Minnesota-based squad become the first privateer team to triumph in the Hypercar/GTP era, it also propelled Laurin Heinrich – winner of both the 24 H. of Daytona 24 and the 12 H. of Sebring with Porsche Penske Motorsport – to the top of the drivers’ standings ahead of Porsche’s full-season factory drivers.
It is an unusual situation, but one Porsche appears perfectly comfortable with. The German manufacturer even reshuffled the 24-year-old’s programme to maximise his chances of fighting for the IMSA title.
“We had originally planned for me to compete in the 24 Hours of Spa-Francorchamps and skip Watkins Glen,” Heinrich explained. “Thanks to Porsche Motorsport and the Schumacher CLRT team for allowing me to drive for JDC-Miller MotorSports in the IMSA race after all, which will hopefully keep my title hopes alive.”
The JDC-Miller Porsche 963 continues to run in 2025 specification, allowing it to benefit from a significantly more favourable Balance of Performance than the 2026-spec factory cars. That includes a 15 kg weight advantage as well as additional power.
Heinrich will, however, have to rely on Tijmen van der Helm and Kaylen Frederick, a line-up that arguably lacks the experience of Porsche Penske’s factory crews.
That only makes this fascinating intra-Porsche battle even more intriguing.
Can Cadillac keep its momentum going?
Has the Cadillac V-Series.R become the benchmark in GTP? That remains difficult to answer given how heavily the Porsche 963 has been restricted by the Balance of Performance since its dominant start to the season.
One thing is certain, however: no manufacturer has displayed the same consistency. More specifically, it is the #31 Action Express Racing Cadillac that continues to impress, outperforming the two Wayne Taylor Racing entries on a regular basis.
Jack Aitken, the car’s only full-season driver, has stood on the podium at every round so far this season. Victory alongside Earl Bamber on the streets of Detroit moved him to the top of the drivers’ standings, while Cadillacand AXR also lead both the manufacturers’ and teams’ championships.
That momentum carried over to the 24 Hours of Le Mans, where the V-Series.R once again demonstrated its outright pace. Aitken recorded the fastest lap of the entire event for the second consecutive year during Hyperpole 2.
Although victory ultimately slipped away in France, Cadillac appears to have reached a level of maturity that allows it to fight at the front regardless of circuit characteristics.
The #31 crew certainly has everything it needs to prevent Porsche Penske Motorsport from claiming a third consecutive GTP title.
Has BoP got the better of Porsche Penske?
After dominating both Daytona and Sebring, Porsche Penske Motorsport has paid a heavy price for its outstanding start to the season. At Detroit, the Porsche 963 tipped the scales at 1,100 kg – a staggering 69 kg heavier than the BMW M Hybrid V8.
The Balance of Performance has gradually become less restrictive since then. The Porsche gains 27 kg compared to Detroit, yet it remains the heaviest GTP car on the grid, carrying a 28 kg deficit to Acura, 43 kg to BMW and 41 kg to Cadillac.
“We’ve had to fight hard in the last three IMSA sprint races,” Thomas Laudenbach, Vice President Porsche Motorsport, said. “We’ve lost the lead in the championship and now want to reclaim it. Our factory team, Porsche Penske Motorsport, can play to its full strengths in endurance races such as the one at Watkins Glen. I expect that, with a solid performance, we’ll be in contention for the podium or even victory.”
Porsche Penske Motorsport’s last podium dates back to Long Beach in mid-April. Given the current Balance of Performance, ending that run this weekend would almost qualify as an upset.
Will Manthey pay the price for the clash with the 24 Hours of Spa?
The entry list features several notable changes as a result of the clash with the CrowdStrike 24 Hours of Spa. Manthey has reshuffled part of its GTD PRO line-up, with Michael Christensen and Loek Hartog joining Klaus Bachler aboard the #911 Porsche 911 GT3 R.
At Daytona and Sebring, the Austrian shared the car with Ricardo Feller and Thomas Preining. One question is how quickly Christensen can get back up to speed.
Aside from an outing at the Nürburgring 24 Hours, the Dane has not raced since Petit Le Mans last October. Although Porsche retained him over the winter, he lost his place in the factory 963 programme and now faces the challenge of returning to competition with very little recent race mileage.
The timing matters. After the opening two rounds of the Michelin Endurance Cup, Manthey sits second in the GTD PRO standings, just six points behind Paul Miller Racing and BMW.
Will three drivers prove to be an advantage?
Three drivers or two? Because of the clash with Spa, several manufacturers have opted to run just two drivers per car. Fewer drivers means more track time during practice sessions, but Watkins Glen has always been a circuit that asks different questions.
At 3.4 miles (5.47 km), with just 11 corners and the famous Bus Stop chicane, Watkins Glen is one of the fastest circuits on the IMSA calendar. Only Daytona produces a higher average speed for GTP machinery. That speed comes at a cost.
“Watkins Glen is the most physical race of the year,” stated Philipp Eng, who co-drives the #25 BMW M Hybrid V8 with Marco Wittmann. “It’s very high G-force overall – in the first chicane, in the corner after – and it’s just high speed and full commitment. That makes it not only physically challenging, but also mentally because you’re always traveling at very high speeds. You know that you’re only spending time in high-speed corners. It’s one of the best tracks on the calendar, but also the most challenging in any aspect.”
Traffic only makes life harder. As the third round of the Michelin Endurance Cup, Watkins Glen attracts one of the biggest grids of the season, with 54 cars expected to take the start. For prototype drivers, maintaining concentration while slicing through GT traffic for six hours is a challenge in itself.
Dane Cameron believes Watkins Glen remains unlike anywhere else on the calendar.
“Honestly, for me, (Watkins Glen) stands alone kind of for the rest of the year in terms of the grip. The load on your neck that you have is so far beyond basically anywhere else we go the rest of the year. It’s kind of like being in a different class in a different car. You feel a bit like you’re an F1 driver for the weekend. The commitment is very high, and you don’t ever feel like you rest much. It’s one of the few places you feel like you have to be a bit brave also these days…I think that’s why we all love it so much.”
Then there is another factor: fatigue. For several years now, Watkins Glen has followed the 24 Hours of Le Mans almost immediately on the calendar. For drivers competing on both sides of the Atlantic, June has become one of the busiest months of the year, with Detroit, Le Mans and Watkins Glen arriving in quick succession.
This year’s two-week gap between Le Mans and Watkins Glen has therefore been welcomed throughout the paddock, after the two races were held on back-to-back weekends in both 2024 and 2025.
Interestingly, only three of the 11 GTP entries will run with three-driver line-ups this weekend: the #5 Porsche, the #31 Cadillac and the #93 Acura.
In GTD PRO, Manthey’s #911 Porsche will be the only car in the class to field three drivers.
How to watch
Qualifying and the Six Hours of the Glen will be streamed live on TheStint.com.
Saturday, June 27
Qualifying: 3:40 p.m. ET / 9:40 p.m. CEST HERE
Sunday, June 28
Race: 12:10 p.m. – 6:10 p.m. ET / 6:10 p.m. – 12:10 a.m. CEST
Did you know?
For the first time since the rebirth of the IMSA SportsCar Championship in 2014, the top-class title could be won by a single driver rather than a full-season pairing.
Jack Aitken currently leads the championship on 1,760 points. The Brit moved clear at the top after Frederik Vesti replaced Earl Bamber at Long Beach, preventing the New Zealander from scoring on that occasion.
Laurin Heinrich sits second. After winning both Daytona and Sebring with Porsche Penske Motorsport before claiming victory at Laguna Seca with JDC-Miller MotorSports, the German heads to Watkins Glen 144 points behind Aitken, but just 10 points ahead of Julien Andlauer and Felipe Nasr.