IMSA WeatherTech SportsCar Championship Classes Explained

The IMSA WeatherTech SportsCar Championship features four distinct classes racing on track simultaneously: two Prototype classes (GTP and LMP2) and two Grand Touring classes (GTD PRO and GTD). This multi-class format creates constant overtaking and complex traffic management.

If you are new to endurance racing, the IMSA WeatherTech SportsCar Championship can seem chaotic. You have dozens of cars on the track at the same time, traveling at vastly different speeds, all competing in the same race—but not necessarily against each other.

This is the beauty of multi-class racing.

In the 2026 IMSA WeatherTech Championship, there are four distinct classes divided into two main categories: Prototypes (custom-built race cars) and Grand Touring (GT) (cars based on production street models).

Here is your complete guide to understanding who is racing whom.

The Prototypes

Prototypes are the fastest cars on the track. They are purpose-built racing machines designed purely for aerodynamic efficiency, downforce, and speed. They do not look like anything you would see on the street.

1. Grand Touring Prototype (GTP)

The Pinnacle of Sportscar Racing

  • Top Speed: ~210 mph
  • Horsepower: ~670 hp (Internal Combustion + Hybrid Electric)
  • Driver Lineup: All Professional (Platinum/Gold)

The GTP class represents the absolute cutting edge of motorsports technology. These cars feature sophisticated hybrid powertrains that mate a manufacturer-specific internal combustion engine to a standardized electric motor system.

This class features massive factory involvement from the world’s largest automakers, including Porsche, Cadillac, Acura, BMW, and Aston Martin. Because they are the fastest cars on the track, the overall winner of the race almost always comes from the GTP class.

2. Le Mans Prototype 2 (LMP2)

The Pro-Am Prototypes

  • Top Speed: ~195 mph
  • Horsepower: ~500 hp (Spec Gibson V8)
  • Driver Lineup: Pro-Am (Requires Bronze or Silver drivers)

LMP2 cars look very similar to GTPs to the untrained eye, but they are slightly smaller, less powerful, and lack hybrid systems. Unlike GTP, where manufacturers build bespoke cars, LMP2 is a “spec” class. All teams use a standardized chassis (usually built by Oreca or Ligier) and a standardized Gibson V8 engine.

The defining feature of LMP2 is the driver mandate. Every car must have a mixture of professional drivers and at least one “Amateur” (Bronze or Silver-rated) driver. This class highlights the skill of wealthy privateer drivers competing at terrifying speeds.

The Grand Touring (GT) Classes

The GT classes are where you will see familiar shapes. These cars are built to global GT3 specifications and must be heavily based on road-going supercars and sports cars you can buy at a dealership. They have less aerodynamic downforce and lower top speeds than the Prototypes, making them the “traffic” that the Prototypes must constantly navigate around.

Interestingly, both GT classes use the exact same specification of car. The only difference between them is the drivers behind the wheel.

3. GT Daytona Pro (GTD PRO)

The Factory GT Battleground

  • Top Speed: ~180 mph
  • Horsepower: ~500 hp (Varies by manufacturer, balanced by BoP)
  • Driver Lineup: All Professional (Platinum/Gold)

GTD PRO is the heavyweight division for GT racing. These entries are often directly supported by the factories themselves: Corvette Racing, Ford Multimatic, Porsche Penske, and Lexus Vasser Sullivan.

Because there are no restrictions on driver ratings, these teams hire the absolute best GT drivers in the world. The racing in GTD PRO is incredibly aggressive, as these pros push the limits of the cars for entire stints without making mistakes.

4. GT Daytona (GTD)

The Privateer GT Class

  • Top Speed: ~180 mph
  • Horsepower: ~500 hp (Identical to GTD PRO)
  • Driver Lineup: Pro-Am (Requires Bronze or Silver drivers)

The GTD class uses the exact same cars as GTD PRO—you will see Porsche 911 GT3 Rs, Ferrari 296 GT3s, Aston Martin Vantages, and Mercedes-AMG GT3s in both classes.

The rule that separates them is the Pro-Am requirement. GTD cars must field at least one Bronze or Silver-rated driver (the “Am”). Typically, the Am driver qualifies the car and starts the race, before handing it over to their highly paid Professional co-driver to finish the race.

For aspiring pros and ambitious amateurs, succeeding in the GTD class requires deep telemetry analysis to ensure the Am driver is minimizing their pace deficit (the “Delta”) to the pros.

Understanding Number Plates and LED Panels

To help fans tell the classes apart, IMSA uses a color-coding system on the cars’ number plates and LED position panels:

  • GTP: Black number on a White background. Red LED position lights.
  • LMP2: White number on a Blue background. Blue LED position lights.
  • GTD PRO: White number on a Red background. Red LED position lights.
  • GTD: White number on a Green background. Green LED position lights.

The LED panels on the side of the car show the car’s current running position within its own class. So if a green LED panel says “1”, that is the leader of the GTD class, even if they are 30th on the overall track.

The Challenge of Traffic

The multi-class format is what makes IMSA racing so difficult and dangerous. A GTP car approaching a tricky corner might be traveling 40 mph faster than the GTD car ahead of it.

The Prototype driver must decide in a split second whether to dive aggressively down the inside—risking a crash—or lift off the throttle and wait to pass on the next straight—losing valuable seconds. Over a 24-hour race like Daytona, navigating this traffic cleanly is what separates the champions from the rest of the field.

Want to see how teams dissect driver performance across these different classes? Explore Sector4’s Telemetry Analysis solutions used by teams in IMSA and SRO.