2CV6 under the bonnet The car featured an air-cooled, flat-twin , four-stroke, 375 cc engine, with the notoriously underpowered earliest model developing only 9 bhp DIN (6.5 kW). A 425 cc engine was introduced in 1955, followed by a 602 cc (giving 28 bhp (20.5 kW) at 7000 rpm) in 1968.