The Amphicar Model 770 was developed by German designer Hans Trippel, who had been working on amphibious vehicles since 1932, including the WWII Volkswagen Schwimmerwagen. The Amphicar first surfaced at the 1959 German auto show, and came ashore in the U.S. on April 1, 1961, at the New York Auto Show.
The Amphicar’s engine was mounted at the rear of the craft, driving the rear wheels through a 4-speed manual transmission.For use in the water, the same engine drove a pair of reversible propellers at the rear, with a second gear lever engaging forward or reverse drive.via(wikipedia).
Once in the water, the main gear lever would normally be left in neutral. The powerplant was the 1147 cc engine from the British Triumph Herald 1200.
Many engines were tried in prototypes but the Triumph engine was “state of the art” in 1961 and had the necessary combination of performance, weight, cool running, and reliability.
Updated versions of this engine remained in production in the Triumph Spitfire until 1980. The Amphicar engine had a power output of 43 hp at 4750 rpm, slightly more than the Triumph Herald due to a shorter exhaust.Designated the “Model 770”,the Amphicar could achieve speeds of 7 knots in the water and 70 mph on land.