Supermodifieds are a class of open wheel race car that compete on paved short tracks throughout the United States and Canada. The class was founded in the 1950s and is especially popular in the Western states, the Northeast and Great Lakes regions.

Supermodifieds are generally constructed from aircraft-quality .095 thick chromium-molybdenum ("chromoly") frame tubing with steel and aluminum components. The bodies are fabricated from fiberglass and aluminum. The cars are powered by fuel-injected V8 engines that run on methanol fuel and can produce in excess of 800 horsepower. While big block V8 engines are allowed on the west coast, nearly all competitors choose to run aluminum small blocks of 410-430 cu. in., whereas the cars of the east run the mandatory cast iron big block with aluminum heads bored to the allowable 468 cu. in. Cars in the midwest can run small blocks up to 412 cu. in. or big blocks up to 481 cu. in.

Modern era supermodifieds run a radical offset chassis that is up to 18 in. to the left of center. The engine and driveline components themselves are mounted in a specially-fabricated area placed outside the left side frame rails. The engine is thus a stressed member of the chassis. This allows weight distribution to favor the left side (often as much as 70%) and thereby aid cornering around the left-hand turns of an oval track. The giant wings, (generally 24 sq ft (2.2 m²)' max), mounted on the roll cage of the cars bear a resemblance to those found on sprint cars and serve a similar purpose, designed to produce down force and allow them to make tight turns at high speed. The west coast style cars of ERA and SMRA run a fixed wing, whereas the cars of the east generally run a wing mounted to the suspension or chassis by pneumatic struts. The racing slick tires used on a supermodified are among the widest used in pavement oval racing.