IMSA Weathertech Sportscar

IMSA WeatherTech SportsCar Championship is the top-level sports car series in North America, run by IMSA (International Motor Sports Association) and built around multi‑class endurance racing on road courses and street circuits. It blends factory‑backed prototypes and GT cars in the same race, with separate titles for drivers, teams, and manufacturers.

Overview and history

The current championship was formed in 2014 by merging the American Le Mans Series and the Grand‑Am Rolex Sports Car Series under a unified rulebook. It quickly became the flagship North American endurance series, anchored by blue‑riband events such as the Rolex 24 at Daytona, 12 Hours of Sebring, 6 Hours of Watkins Glen, and Petit Le Mans at Road Atlanta. The series is title‑sponsored by WeatherTech and officially named the IMSA WeatherTech SportsCar Championship.

Class structure and car types

The championship runs four main classes at most events, split between purpose‑built prototypes and GT‑based cars.

IMSA classes table

GTP, LMP2 and GTD are harmonised with 24 Hours of Le Mans regulations so cars can race on both sides of the Atlantic with minor adjustments. Classes are further balanced by a BoP system that adjusts weight, boost, and other parameters to keep lap times within a competitive window.

Calendar, formats, and key races

The series typically runs 11 rounds per season, with a mix of endurance and shorter sprint events.

The season opens with the Rolex 24 At Daytona (24 hours) in January and ends with Petit Le Mans (10 hours) at Road Atlanta in October.

Five races (Daytona, Sebring, Watkins Glen, Road Atlanta, and one additional long race) form the Michelin Endurance Cup, a sub‑championship for long‑distance specialists.

Not every event uses every class; for example, some shorter races are GT‑only, and a few do not include GTP to manage costs and logistics.

Typical IMSA weekend structure

IMSA weekends are “compressed” compared with some series, often running over three days with reduced practice to save travel and track‑rental costs.

Practice: Usually two or three practice sessions totals around 2–3 hours of track time for each class group.

Qualifying: 15‑minute sessions per class, often run back‑to‑back, with no work allowed on the car before the session ends; cars must start the race on their qualifying tyres.

Race: Main races range from 2 hours 40 minutes for “sprint” rounds up to 24 hours at Daytona; all classes share the track, so overtaking traffic is a constant strategic element.

Points, championships, and titles

IMSA crowns multiple champions each year, with separate points tables for drivers, teams, and manufacturers in each class.

Points system (WeatherTech Championship)

Race points are awarded to every finisher in class, with a relatively flat scale compared with Formula One to reward depth of results.

Race winners receive 350 points, second place 320, third 300, fourth 280, fifth 260, then decreasing in steps of 10 (250, 240, etc.) for lower positions.

Qualifying points are worth 10% of race points, so pole earns 35 points, second in qualifying 32, and so on, giving teams an incentive to take qualifying seriously.

Each car is treated as its own “team” entry for team points, even if a manufacturer runs multiple cars under the same banner.

Manufacturer points are based only on the best‑finishing car from each make in each class; if one brand finishes 1st and 2nd, it only gets first‑place points, and rivals move up.

The Michelin Endurance Cup uses separate “in‑race” points at set intervals (for example, 6, 12, 18 hours in a 24‑hour race). The class leader at each segment gets 5 points, second 4, third 3, and all other running cars 2, rewarding consistent long‑run performance regardless of the final finishing position.

Driver ratings, line‑ups, and strategy

IMSA uses the FIA’s driver‑rating system (Platinum, Gold, Silver, Bronze) to shape line‑ups and maintain pro‑am character in some classes.

GTP and GTD Pro: No rating restrictions; teams can run all‑pro line‑ups and rotate drivers around strategy and fatigue.

LMP2: Pro‑am; typically three drivers for long races, with at least one Bronze and only one Gold allowed. The Bronze often qualifies and starts in long events.

GTD: At least one Bronze or Silver “am” is required, so pro drivers must manage risk while giving their amateur teammates enough minimum drive time.

Endurance races usually require three or four drivers per car, each meeting minimum and maximum drive‑time rules to prevent a single driver from doing an extreme majority of the race. Multi‑class traffic management, drive‑time planning, and avoiding penalties under full‑course yellow or safety‑car procedures are core strategic elements.

Safety cars, yellows, and race control

Like other endurance series, IMSA uses full‑course yellows (FCYs) and safety‑car procedures rather than virtual safety cars.

Full‑course yellow: All cars slow to a controlled pace behind the safety car; pits are often initially closed to avoid huge strategic swings, then opened in a structured way by class.

“Pass around” and “wave‑by” rules let cars that are between the safety car and their own class leader move to the back of the line, so lapped‑traffic distortions are minimised.

Race control can use a “short yellow” procedure late in races to clean minor incidents quickly without going through the full wave‑by cycle, to maximise green‑flag racing.

Local yellows, blue flags, and other standard flag procedures supplement FCYs, but in endurance multi‑class traffic, the ability of faster classes to respect slower GT cars under yellow and in blind corners is a constant safety focus.

Position in the global sports car ladder

The IMSA WeatherTech SportsCar Championship sits alongside the FIA World Endurance Championship as a top‑tier destination for works‑backed prototype and GT programmes.

GTP cars are designed to be cross‑eligible with the WEC Hypercar category, so manufacturers can run similar programs at Daytona, Sebring, Le Mans, and other global events.

LMP2 and GTD/GTD Pro share technical bases with Le Mans, GT World Challenge, and other GT3 series, making IMSA a key part of the global sports‑car ecosystem and driver ladder.

For American and international manufacturers, IMSA offers high‑profile exposure at iconic U.S. circuits plus technical freedom in areas like hybrid systems and GT3 development, tied together by Balance of Performance and a points system tailored to long‑distance