A kit car is a vehicle typically built from a kit ordered from a company which specializes in or exists only to sell parts either to create an entirely new vehicle or a replica of an older vehicle, or to enhance an existing vehicle to the point where it is essentially an entirely new thing. The most popular kit cars are replicas, for example of the Shelby Cobra which makes up approximately 70% of all kits sold, or the Ford GT40. In most cases, replica kit cars are technically superior to the original, though obviously of far lesser monetary value. Kits which upgrade an existing vehicle are also extremely popular, and those which upgrade the (original) Volkswagen Beetle (or "bug") seem to be the most plentiful, probably due to the extremely low cost and high availability of such a platform, plus the added advantage that it is simple to swap a more powerful Corvair powerplant into them.

Kit cars range in cost from a couple of thousand dollars (for the cheaper VW kits) up to cars like GT40 kits which will cost around $60,000 to complete. They can usually be purchased in various states of assembly, including (for some models) fully completed. Often there are cars represented by kits from assorted manufacturers, especially the famous Fords, and many of them are built at least partially on the original plans but typically of more modern materials.