This guide to all the main aspects of downforce devices relevant to the principal competition car classes should be of interest to competition drivers, both amateur and professional constructors and designers of competition vehicles, and manufacturers and assemblers of kit cars, all seeking to improve performance and handling. It includes: downforce-inducing and lift-reducing devices from the early days to the present; data from major constructors, interviews with experts, and reports from race team bases; the theory of downforce lift and drag for road vehicles; wind tunnels and computational fluid dynamics; airdams, splitters, spoilers and wings; manufacturers of downforce-inducing parts; case studies from Formula 1, IndyCar, Formula 3000, Formula 3, sports cars, saloons, rally cars, club formulae, hillclimb and sprint cars, dragsters and motorcycles; and legislation, restrictions and regulations.