THE VW Beetle, that icon of post-war German motoring has proved itself to be one of the most desirable collectors' cars in the world.

But there is one version that has Beetle fans on the edge of their bucket seats if one comes on the market in perfect original condition.

I'm talking about the Beetle Cabriolet which has its origins in 1948 when Wilhelm Karmann first bought a VW Beetle sedan and converted it into a four-seater convertible.

The car held great promise, resembling the pre-war VW38 prototype in which Adolf Hitler rode at the factory cornerstone ceremony in 1938.

Such was the enthusiasm for the Cabriolet that production began at the Karmann factory in Osnabruck in 1949.

It might be imagined that the Cabriolet was just a Beetle with a soft top, but it was much more.

To compensate for the strength lost in removing the roof, the sills were reinforced with welded U-channel rails, a transverse beam was fitted below the front edge of the rear seat cushion, and the side cowl-panels below the instrument panel were double-wall.

In addition, the lower corners of the door apertures had welded-in curved gussets, and the doors had secondary alignment wedges at the B-pillar.

The top featured a full inner headliner hiding the folding mechanism and crossbars.

Ittucked back pram style and could be housed in a smart cover because there was nowhere for it to go because of the rear engine.

The hood was extremely well made. In between the two top layers was one inch (25mm) of insulation. The rear window was tempered safety glass, and, after 1968, heated.

Due to the thickness of the top, it remained quite tall when folded. To enable the driver to see over the lowered top, the inside rearview was mounted on an offset pivot. By twisting the mirror 180 degrees on a longitudinal axis, it would rise approximately two inches.

Better equipped than the sedan, the Cabriolet featured dual rear ashtrays, twin map pockets, a visor vanity mirror on the passenger side, rear stone shields, and, in 1969, wheel trim rings. Many of these items did not become available on other Beetles until the advent of the optional "L" trim level of 1970.

The last of 331,847 cabriolets came off the production line on 10 January 1980.