IMSA WeatherTech SportsCar Championship

Sanctioning body IMSA was founded in 1969 and has run various iterations of America's top-level sportscar championship since then. In its current guise, the inaugural season took place in 2014, and was initially known as the United SportsCar Championship. The current championship’s first year included 13 rounds, beginning with the Rolex 24 at Daytona and culminating in Petit Le Mans at Road Atlanta. It rebranded to its current name for the 2016 season.

The IMSA calendar consists of 11 rounds, including five races which form the Michelin Endurance Cup. There are two rounds which do not feature the top class, GTP, at Mosport and Virginia International Raceway. The season once again starts with the Daytona 24 Hours in January and ends at Road Atlanta for the iconic Petit Le Mans in October.

Like the World Endurance Championship, the IMSA SportsCar Championship features two types of cars – Prototype and GT. They are split into four classes: Grand Touring Prototype (GTP), Le Mans Prototype 2 (LMP2), GT Daytona Pro (GTD Pro) and GT Daytona (GTD). GTP cars are the fastest, and are designed for the track, while GT entries are based on production models. The GTP class uses rules similar to that of the World Endurance Championship, allowing cars to compete in both GTP and the WEC’s Hypercar category.

Porsche Penske Motorsport competes in the top tier of IMSA: The GTP class. There are two factory Porsche GTP entries, while Proton Competition Mustang Sampling and JDC-Miller MotorSports also run one Porsche 963 each. Across GTD Pro and GTD, there are four Porsche 911 GT3 R, run by Proton Competition, AO Racing, Iron Dames and Wright Motorsports.

Porsche has over 600 wins in the IMSA SportsCar Championship, reaching that milestone with the #6 car’s GTP victory at Laguna Seca, while Team Penske clocked up its 100th sportscar win at the same race. The Porsche 963 took its first win - after just three races - at Long Beach in 2023 to begin a stellar run of results in its first two seasons in the championship.