Felix Heinrich Wankel (1902-1988) was the German inventor and developer of the practical rotary combustion engine (patented 1929), now known as the Wankel engine. In the Wankel engine, the four strokes of a typical Otto cycle engine are arranged sequentially around an oval, unlike the reciprocating motion of a piston engine. The power of a Wankel is generally higher than that of a four-stroke engine of similar displacement. Compared to a reciprocating engine, the Wankel engine is simpler, lighter, contains far fewer moving parts and can burn lower octane fuel without preignition or knock. However, the Wankel produced incomplete combustion and therefore high emissions. It is also difficult and expensive to expand the size of the Wankel engine. They typically consume more fuel than a piston engine because the thermodynamic efficiency of the engine is reduced by the long combustion-chamber shape and low compression ratio. Mazda was the only carmaker to aggressively develop the rotary engine in its cars.
Felix Wankel (Encyclopaedia Britannica)