A straight-three engine is a three-cylinder piston engine where cylinders are arranged in a line along a common crankshaft.

The Syrena was a Polish automobile model first exhibited at the Poznań Trade Fair in 1955 and manufactured from 1957 to 1972 by the Fabryka Samochodów Osobowych (FSO) in Warsaw and from 1972 until 1983 by Fabryka Samochodów Małolitrażowych (FSM) in Bielsko-Biała. 177,234 were manufactured by FSO and 344,077 by FSM, a total of 521,311. During its remarkably long production run it underwent only minor modifications.