August 1958 to September 1959
By 1958 sales of Speedsters in the USA had started to decline (sales in 1957 were around 1500) and Porsche were worried that that buyers were limited to weekend racers and enthusiasts and only in the sunshine states like California.
Some Americans disliked the bucket seats and the general lack of comfort and weather protection. If they wanted to increase sales in wetter and colder climates, like most of Europe, Porsche felt that they had to modify the product offering. Another reason driving the change was the small profit margin for both factory and dealers.
Porsche still felt it necessary to have a car a bit more basic and less expensive than the 356 Coupes and Cabriolets to compete with the small British sports cars.
Because the increasing production levels of the 356 range were putting a strain on existing facilities at Reutter, Porsche contracted the production of the new car to coachbuilder Drauz at Heilbronn – hence the ‘D’ in the name
The first few prototypes had Speedster scripts before they were removed in the production run.
The seats, skimpy top and side curtains were seen as the main defects of the Speedster. The new car had conventional wind up windows and a more substantial hood. The additional headroom was welcomed by normal size drivers who had problems driving the Speedster with the top up.
Mechanically, the Convertible D was Identical to the 356A (T2) Speedsters – all the changes were really to do with comfort and weather proofing.
The new car was heavier and less aerodynamic than the Speedster but still had good performance compared with other sportscars of the day
As well as a taller windscreen with straight sides, allowing better sealing with the side windows the Convertible D had much more substantial and comfortable seats than the Speedster
For people wanting to know more about the Convertible D, I would strongly recommend the Convertible D Registry website run by John Chatley. It is extremely comprehensive with details of all the Ds they have located, a superb photo gallery and very detailed technical and historical information.
Only 1330 Convertible Ds were produced between August 1958 and September 1959 making it probably the rarest 356 models manufactured for a full year.
The Ds used either the 1600 Normal (Damen) or 1600 Super engines. Only two were equipped with four-cam Carrera Engines.
For the 1960 model year the Convertible D model was replaced by the 356B Roadster based on the new T5 body style.