BMW has once again collaborated with Italian design house Zagato, this time on a convertible that will be displayed at the Pebble Beach Concours d'Elegance in California.

Built almost exclusively as a styling exercise following the warm reception for the BMW Zagato Coupe, the unique Zagato Roadster concept was created in just six weeks.

It's just a model, though, and no drivetrain information has been given for good reason - the Roadster won't be built unless overwhelming demand develops.

In a statement BMW makes the assertion that the Zagato is `ready to drive and intended to be driven at high speeds' but is speaking figuratively. There is much talk of driver-oriented styling and performance intent, but sadly it may never be put to the test.

The company only gives cryptic hints at the `brawny powerplant' and of the car's `aura of dynamism'.

Externally, the presence of small `z' motifs dotted around the construction leaves no doubt as to the origins of its curvaceous, vaguely Z4-ish look. Chunky wheel arches house 19-inch wheels with a hint of the propeller about their styling, offering a nod to both companies' heritage.

The designers had completely free reign with the bodyshell but did not take responsibility for anything else, sticking firmly to the coachbuilding tradition.

The interior, left entirely to BMW, is clear and structured in the manner of all the company's modern models, albeit adorned with a continuous strip of leather that runs all the way around the cabin even taking in the roll bars.

Zagato, led by company chiefs Andrea Zagato and Marella Rivolta-Zagato, was founded in 1919 and is claimed to be the only automotive coachbuilder to still remain in independent ownership.