The Lada Оkа is a city car designed in the Soviet Union in the later part of the seventies by AvtoVAZ. It entered production in 1988 powered by a 644 cc (39.3 cu in) SOHC two-cylinder engine. While developed at AutoVAZ by a team led by Yuri Kuteev, no production models were built there. Instead, manufacturing was outsourced to SeAZ factory in Serpukhov and ZMA in Naberezhnye Chelny. Massive plans were in place for a new plant in Yelabuga, but these failed to materialize. The car was also produced in Azerbaijan by the Gyandzha Auto Plant. The name comes from the Oka River in Russia upon which Serpukhov is situated.

A straight-twin engine, also known as an inline-twin, vertical-twin, or parallel-twin, is a two-cylinder piston engine whose cylinders are arranged in a line along a common crankshaft.