D Sports Racing is a Sports Car Club of America class for purpose-built, 'LeMans-style', closed wheel roadracing cars. It has been called the one racing category that remains unfettered by regulations that have throttled innovation elsewhere in motorsport. Usually known simply as DSR, the class began in 1968. DSR evolved from the SCCA's older H Modified class, which traces its roots back to the early 1950s. Today's DSR cars normally use a 1000cc four cylinder engine sourced from a Japanese motorcycle. Several other engines are allowed - see the SCCA Rulebook