5. Suzuki RE-5
The RE5 was a motorcycle with a liquid-cooled single-rotor Wankel engine, built by Suzuki from 1974 through 1976. Apart from its unique engine design, the RE5 is otherwise a conventional roadster. Compared to conventional piston engines, rotary engines are smooth, lightweight and compact, capable of producing high power outputs from relatively small engine displacements. Although these attributes are highly beneficial to motorcycles, Wankel-engined based bikes remain something of a rarity, even though the rotary engine design had once been thought to be the future of motorcycling. The Suzuki RE5 was one of only a handful of Wankel engined motorcycles ever built.