Following BMW’s striking BMW Zagato Coupé concept at the Villa d’Este Concours in May, the Bavarian marque has now unveiled a one-off roadster version at the 2012 Concours d’Elegance.

Based on the BMW Z4 sDrive35is drivetrain, power for the new roadster (and preceding coupé model) is derived from BMW’s turbocharged 3.0-litre, six-cylinder engine. It receives increased boost pressure, an altered exhaust system and modifications that increase power from 335bhp in standard guise to 400bhp.

The Zagato roadster has been designed and hand-built in just six weeks, and it shares much of the coupé’s detailing, which includes its sculpted bonnet with integrated cooling ducts and low-set kidney grille with z-design grating.

 Also akin to the coupé concept is the roadster’s bumper and 19-inch alloy wheel design, plus prominent cooling ducts in each front wheel arch. At its rear, Zagato has given the roadster a slightly revised version of the coupé’s bumper and tweaked the design of the model’s twin exhaust pipes.

To mirror the coupe’s twin-dome roof – a Zagato hallmark – the roadster’s soft-top roof cover features a double-bubble theme. Inside the BMW Zagato Roadster’s cabin, its brown leather seats feature colour-contrasting stitching, as does the leather steering wheel and centre console. The seats are also embroidered with a ‘z’ emblem.

The most striking difference between both Zagato models is their colour. ‘Brilliant’ grey is used for the drop-top, which compares with the coupé’s red paintwork.

Although design boss Karim Habib denied plans to place the Zagato coupé into series production, he did suggest that it could be made in limited numbers at a price that would likely double the standard car’s price-tag. If the demand is there, the roadster variant could face the same fate.