The Subaru 1000 was the first front wheel drive Subaru produced by Fuji Heavy Industries that was in the Japanese government 'compact car' classification starting in 1966. It was the first production Subaru to use a boxer engine. In 1963, Subaru introduced the Subaru 1000. For compactness and to ensure quietness of operation with vibration kept to a minimum, the engine was developed with water cooling instead of the originally intended air cooling in the A-5 concept.The Subaru 1000 was formally introduced on October 21, 1965. The two-door sedan, model A512 was introduced February 15,1967, with a four-door van released September 14, 1967. These cars featured a unique water-cooled, horizontally opposed four-cylinder engine, with overhead valves operated by push rods. As was typical of early front wheel drive cars, the 1000 featured inboard drum brakes up front to reduce unsprung suspension weight and an easier implementation of an independent front suspension. Other unique features of the 1000 were a lack of a heater core, the heating system took its warmth directly from the radiator, and a hybrid suspension system that used torsion bars in combination with coil springs.