IMSA: North America's sports car championship and its three great endurance races.

What IMSA is

IMSA, the International Motor Sports Association, sanctions professional sports car racing in North America. Speed Sport's history of the organisation says it was founded in 1969 by John and Peggy Bishop together with NASCAR founder Bill France Sr., who put up most of the money and at first held 75% of the stock. Its first race, at Pocono Raceway on 19 October 1969, was for formula cars rather than sports cars.

Wikipedia (secondary) describes IMSA today as a NASCAR subsidiary based in Daytona Beach, Florida, and says the current championship grew out of the 2012-2013 merger of the American Le Mans Series and Grand-Am. IMSA is also one of the six member clubs of ACCUS, the body that links US sanctioning organisations to the FIA. Our governing bodies page explains how those layers fit together.

The WeatherTech SportsCar Championship

The WeatherTech SportsCar Championship is IMSA's top series. Four classes race on track at the same time, each with its own results and standings. RACER's class guide describes them like this:

Wikipedia (secondary) adds that GTP admits prototypes built to both the LMDh and LMH rules and that LMP2 cars share a spec Gibson GK428 V8 engine. RACER notes that each car carries coloured LED panels on its sides showing its position within its own class.

How points work

Points are scored within each class at every round. IMSA's own 2021 explainer gives 350 points for a class win, 320 for second and 300 for third, with 35 points for class pole and 32 for the second-fastest qualifier. Those values come from an older IMSA article and were not separately confirmed for 2026. Wikipedia (secondary) says manufacturer points go only to each make's best-placed car in a class.

The long races also count toward the Michelin Endurance Cup, a separate title. IMSA explains that it pays 5, 4, 3 and 2 points to class positions at fixed points during the race: twice in six-hour races, three times at Sebring and Petit Le Mans, and four times at the Rolex 24. At the 2026 Petit Le Mans those payouts came at hours 4, 8 and 10. For how practice, qualifying and pit stops fit into a weekend, see the race weekend.

The three endurance classics

Rolex 24 at Daytona

The Rolex 24 is run in January at Daytona International Speedway and, as the name says, lasts 24 hours.

• 2025 (63rd running): IMSA and Porsche report that the No. 7 Porsche Penske 963 of Felipe Nasr, Nick Tandy and Laurens Vanthoor won. Porsche counted it as its 20th overall win at Daytona and said Tandy became the first driver with overall wins at Daytona, Le Mans, the Nurburgring 24 Hours and the Spa 24 Hours.
• 2026 (64th running, 24 to 25 January): the No. 7 Porsche Penske 963 of Nasr, Julien Andlauer and Laurin Heinrich won by 1.569 seconds over the No. 31 Whelen Cadillac after 705 laps, according to IMSA and Porsche. That made three Rolex 24 wins in a row for both the team and Nasr, and IMSA says Nasr joined Helio Castroneves and Peter Gregg as the only drivers to win overall three years running. Porsche called it the make's 21st overall victory there. RACER reports the result, first issued as provisional, was confirmed after inspection.

Wikipedia (secondary) records that fog caused a caution period of about six and a half hours overnight in 2026, and lists the class winners as the No. 04 CrowdStrike Racing by APR car (LMP2), the No. 1 Paul Miller Racing BMW M4 GT3 Evo (GTD Pro) and the No. 57 Winward Racing Mercedes-AMG (GTD).

Twelve Hours of Sebring

The Twelve Hours of Sebring is the second of the three classics in the calendar year.

• 2025: Wikipedia (secondary) lists the No. 7 Porsche Penske car of Nasr, Tandy and Vanthoor as overall winner. NBC Sports describes the 2026 win as the team's second straight at Sebring, which fits, but the 2025 crew was not checked against an official page.
• 2026 (March): IMSA reports another Porsche Penske one-two. Sportscar365 and Porsche name the No. 7 Porsche 963 of Nasr, Andlauer and Heinrich as winners by 1.515 seconds over the sister No. 6 car. Porsche says it was the make's 20th overall Sebring win and the team's second straight Daytona and Sebring double. Manthey's No. 911 Porsche, driven by Thomas Preining with Bachler and Feller, won GTD Pro.

Petit Le Mans

Motul Petit Le Mans, a 10-hour race at Road Atlanta, is the season finale. In early October 2026 it was won overall by the No. 6 Porsche Penske 963. NBC Sports reports that Laurens Vanthoor held off the No. 24 BMW by 1.205 seconds at the finish, and Wikipedia (secondary) lists his co-drivers as Matt Campbell and Kevin Estre. The exact race date is given differently: Wikipedia says 4 October 2026, while IMSA's article on the result carries a 3 October date.

Champions

2025

Per IMSA's Night of Champions coverage and NBC Sports:

2026

The 2026 season is finished. Going into the Petit Le Mans finale, Wikipedia (secondary) shows the No. 31 Whelen Cadillac leading the GTP teams' standings and Cadillac leading the GTP manufacturers. IMSA honoured its champions at its Night of Champions, reported on 5 October 2026; this table follows Sportscar365's copy of the IMSA release:

The same release gives the 2026 Michelin Endurance Cup titles: in GTP, Nasr, Andlauer and Heinrich with Porsche Penske Motorsport and Porsche; in LMP2, Kurtz, Quinn and Toby Sowery; in GTD Pro, De Phillippi and Verhagen with BMW; and in GTD, Ward and Ellis, with Ferrari as the Endurance Cup GTD manufacturer. That is why two makes appear for GTD in 2026: Mercedes-AMG took the season manufacturers' title and Ferrari the Endurance Cup one.

The rest of the IMSA ladder

IMSA sanctions several other series that often share the WeatherTech weekends. Wikipedia (secondary) lists the Michelin Pilot Challenge (GT4 and TCR cars), the VP Racing SportsCar Challenge (LMP3 and GT4), and single-make series including the Porsche GT3 Cup Challenge USA by Yokohama, Ferrari Challenge, Lamborghini Super Trofeo, the Mazda MX-5 Cup and the Mustang Challenge. IMSA publishes a 2026 Mustang Challenge event schedule, and Performance Racing Industry reports that the VP Racing SportsCar Challenge grew to 10 events for 2026.

For the wider world of prototypes and GT cars, including the FIA World Endurance Championship that shares GTP-type cars with IMSA, see endurance racing and Le Mans and sports cars and endurance.