Late Model stock car racing, also known as late model racing and late models, refers to a type of auto racing that involves purpose-built cars simultaneously racing against each other primarily on oval tracks. This type of racing was early-on characterized by its participants' modification to the engines of post-World War II passenger cars, but the modern day understanding references a class that allows considerable modifications to both the engine and body, yet requires some form of front fender package.

As the post WWII auto industry began meeting demand for new cars, auto lots were filling up with the pre-war coupes and sedans. These 1939-1941 cars, "modified" with souped up engines, were finding their way to competitions at racing ovals converted from horse racing or newly carved out in fields. In 1948 NASCAR became one of the first organizations to standardize the rules to ensure equal competition.

The rulebook mandated that all cars had to be American made, and 1937 or newer, with full stock fenders, running boards and bodies if equipped by the factory, but their bumpers and mufflers had to be removed. Also, a car's wheelbase, length and width had to remain stock, as did the hood. Two years later NASCAR added a division for "lesser modified" cars, which they distinguished as the Sportsman. Specifications for the Sportsman cars mirrored the Modified rules as to bodies and safety, but restricted the degree of engine modifications.

As NASCAR’s Grand National cars aged out (current model year and two most recent years only) they became eligible to compete in the Modified and Sportsman division. By 1956 NASCAR had developed a plan to phase out the pre-war coupes and sedans in favor of "Late Models", identified as American cars produced between 1949 and 1955.

Looking to differentiate the Sportsman as a truly separate class, in 1968 NASCAR updated their rules to require 1955 and newer bodies, rebranding the class the Late Model Sportsman Series. NASCAR later reorganized the championship points and events into the touring series that became the Xfinity Series. Earlier car models remained eligible for the Modified division, which evolved to eliminate front fenders.

Since that time, the various sanctioning organizations have developed countless rule packages, but for the last half of century, the "Late Model" class distinction has had little to do with the model year of the car.

In the late 1970s the costs for the Late Model Sportsman cars became excessive, so the "Late Model Stock Car" was born. Within a few years changes began with the carburetor, and by the mid-1980s the stock front chassis was replaced with a racing clip, for safety and availability. The Late Model that exists today is a full-blown race car with race parts.

Late model race cars now include super late models which have looser rules; late model stock cars and pro late models where cars are more aerodynamically aggressive with lighter bodies and enhanced horsepower; and limited late models which have less horsepower. Vehicles built to race on dirt tracks are significantly different from vehicles raced on asphalt.