IMSA WeatherTech SportsCar Championship
SPORTSCAR RACING MADE IN USA
The IMSA (International Motor Sports Association) is one of the most important US motorsport organisations and is therefore responsible for various racing series. With the IMSA WeatherTech SportsCar Championship (IWSC), founded in 2013, the organisation is continuing the long tradition of prestigious sports car races in North America.
The championship calendar traditionally includes a combination of sprint and endurance events. Three of the world's most prestigious endurance races are part of the IWSC: the Rolex 24 At Daytona, the Mobil 1 Twelve Hours of Sebring and the Motul Petit Le Mans. These highlight events are also included in the IMSA Michelin Endurance Cup (IMEC). The IMEC classification is based on endurance results only.
In the supporting programme, we are represented in the IMSA Michelin Pilot Challenge and the IMSA VP Racing SportsCar Challenge.
2025 season
We enter the ten-race 2025 season as defending champions in all GTD classifications. Reigning drivers' champions Philip Ellis and Russell Ward again compete in all races for Winward Racing. Indy Dontje, another reigning champion, completes the line-up in the Michelin Endurance Cup.
Lone Star Racing and Korthoff Competition Motors each field another Mercedes-AMG GT3. The ten-hour season finale, the Motul Petit Le Mans, takes place on 11 October.
Further information about the IMSA




2024
Champion of all classes
With six out of six possible GTD titles, the 2024 season is our most successful to date in the US series. By winning the endurance classics at Daytona, Sebring and Watkins Glen, Winward Racing with Indy Dontje (Endurance Cup only), Philip Ellis, Daniel Morad (Daytona only) and Russell Ward lay the foundation early on for winning the team classifications in the overall standings and in the endurance classification. With another victory in the sprint race at Laguna Seca, Winward Racing secures a total of four GTD class wins in 2024. Both GTD drivers’ and manufacturers’ championships also go to Affalterbach.




2023
Endurance Cup masterclass
In 2023, our Customer Racing Teams secure the titles in the drivers’, team and manufacturers’ standings of the Michelin Endurance Cup in both GTD classes. WeatherTech Racing celebrates a total of four GTD PRO race wins with Jules Gounon and Daniel Juncadella. Together with Maro Engel, they win the Rolex 24 At Daytona and, for the first time, the Motul Petit Le Mans. Korthoff/Preston Motorsports and Winward Racing make a decisive contribution to winning the GTD drivers’, team and manufacturers’ championships in the Michelin Endurance Cup.




2021
Daytona milestone
The Rolex 24 At Daytona has been the major endurance highlight in the USA since its inaugural edition in 1962. In 2021, we achieve a historic success on the legendary Florida circuit: In the high-calibre GTD category, we celebrate a one-two victory with the Mercedes-AMG GT3, which is also our first win in the 24-hour race at Daytona International Speedway. After 745 laps, Winward Racing with Indy Dontje, Philip Ellis, Maro Engel and Russell Ward wins ahead of SunEnergy1 Racing.






2017
Debut year endurance champions
The 2017 season sees our Mercedes-AMG GT3 make its debut in the North American IMSA SportsCar Championship. The first successes come quickly: Riley Motorsports – Team AMG wins the 12 Hours of Sebring at the first attempt with Jeroen Bleekemolen, Mario Farnbacher and Ben Keating. Thanks to further top finishes during the course of the season, we secure all three GTD championships in the Endurance Cup together with the US team and the three drivers.