Bentley has taken the roof off its ultra-exclusive Batur to create its most expensive car yet – and one of the most powerful combustion convertibles to come out of Britain.

The new drop-top is the third bespoke model line from Bentley's Mulliner coachbuilding division, following the coupé on which it is based and the closely related Bacalar barchetta – although unlike the latter, this new model does feature a retractable roof. 

Just 16 examples will be built, each featuring extreme levels of personalisation and costing its owner comfortably more than £2 million.

Derived from the Continental GT, the new two-seater will be one of the last cars to feature Bentley's 6.0-litre twin-turbocharged W12 engine, which ends production in the summer.

Here, as in the Batur coupé, it is tuned to give 740bhp and 738lb ft, and while Bentley has not given full performance figures, it's expected to match the hard-top's 3.4sec 0-62mph time and 209mph top speed.

No two examples of the machine will be alike, with the scope of personalisation offered by Mulliner meaning that the customers are "limited only by their imagination" when it comes to designing their car.

They can choose the colour and material used for "practically every surface", says Bentley, with an "infinite" paint choice on offer, along with hand-painted graphics, different types of finish for the metal bodywork trim and even an ombré-style effect for the front grille.

So too can customers choose the material used for the convertible top itself, and the wraparound cockpit can be optionally decorated throughout with 3D-printed rose gold trim elements – including the 'organ stop' vent controls.

Confirmation that the Batur Convertible will be "one of the last ever" models to feature Bentley's biggest engine suggests the W12 is not ready to retire just yet, and further 12-pot special editions could come before the firm replaces the motor with a new V8 hybrid arrangement for its core models.