Do not be fooled by the cold alphanumerics of its model name: The Porsche 356 A 1600 Convertible D by Drauz is a completely charming variant of the pivotal mid-century German sports car, and among the most collectable.

It also came about at an important juncture in the evolution of Porsche’s model lineup.

Porsche’s simple, purpose-driven 356 Speedster, designed to bolster the marque’s motorsports credibility, had exceeded all expectations on the racetrack—but it was perhaps a bit too bare-bones to ever be widely marketable, and it was phased out in 1958.

The 356 B Roadster that would arrive for 1960 offered similar styling, but with an added dose of luxury.

In the interim, Porsche commissioned coachbuilder Drauz of Heilbronn, Germany to create a special run of cars to fill the gap.

The new car added such amenities as a wind-up door glass in place of side curtains, a taller windshield, a better top, and a more luxurious interior.

Porsche sales literature described the new Converti...