1973 Mazda Ad, "Introducing the Only Rotary Engine Car in America, Mazda"

Mazda introduced its first production rotary engine, based on a design by German engineer Felix Wankel, in Japan in 1967. Instead of conventional reciprocating pistons, the rotary powerplant used an eccentric rotor to convert internal combustion power into motion. Mazda brought its rotary engine to the American market for 1974. Though compact and lightweight, rotary engines tended to be less fuel efficient.