In 1932, Ferdinand Porsche produced prototypes for the NSU company of Germany. These led to the design of the Volkswagen. The prototypes had a rear, air-cooled engine, torsion-bar suspension, and the spare tire mounted at an angle in the front luggage compartment. In 1936, Porsche produced three Volkswagen prototypes, one of which was a 995 cc., horizontally-opposed, four-cylinder automobile. In 1945 Volkswagen production began and 1,785 Beetles were built. The Volkswagen convertible was introduced in 1949, the year when only two Volkswagens were sold in the entire U.S.A. The year 1950 marked the beginning of the sunroof models and the transporter series. The Volkswagen Karmann Ghia was introduced in 1956, and is still of the same basic styling format. The "big" Volkswagen, the 1500 Squareback, was introduced in Europe in 1961, and sold in the U.S.A. in 1966 as a member of the new type 3 series (Fastback and Squareback).