While the 356's body was an original design by Porsche employee Erwin Komenda, its mechanicals (including engine, suspension and chassis) were derived from the Volkswagen. The first 356, was road certified in Austria on June 8, 1948, and used many Volkswagen parts for manufacturing economy. Porsche quickly re-engineered and refined the car with a focus on performance. By the late 50's many fewer parts were shared in common between Volkswagen and Porsche. The early 356 automobile bodies produced at Gmünd, Austria were handcrafted in aluminum, but when production moved to Zuffenhausen, Germany in 1950, models produced there were steel-bodied. Little noticed at its inception, the first 356s sold primarily in Austria and Germany.
From the first prototype in 1948, it took Porsche about two years to manufacture the first 50 automobiles. By the early 1950s the 356 had gained some renown among enthusiasts on both sides of the Atlantic for its aerodynamics, handling, and excellent build quality. It was common for owners to race the car as well as drive it on the street. Increasing success with its racing and road cars brought Porsche orders for over 10,000 units in 1964, and when 356 production ended in 1965 approximately 78,000 had been produced.
A number of companies make replicas of the Speedster, most of them with VW engines similar to the original but others based on a variety of platforms. Companies include: Apal, Banham, Chesil, Covin, Intermeccanica and Vintage Speedsters.
Source: Wikipedia Porsche 356 Speedster Article.