The most powerful W12-engined Bentley – the highly exclusive Batur Convertible – has begun its final suite of sign-off testing. Created by Mulliner, Bentley’s in house bespoke division and the longest standing coachbuilder in the world, the Batur Convertible is the third car in Mulliner’s Coachbuilt family, following the Bacalar barchetta and the Batur coupe. Strictly limited to just 16 units, the Batur Convertible is the most powerful W12-powered drop-top Grand Tourer in Bentley’s history.

Bentley announced the retirement of the W12 engine earlier this year, with the last engine leaving the production line in July. The 16 customer examples of the Batur Convertible will be among the recipients of the final W12 engines, each producing 750 PS as the most powerful iteration of the engine ever developed.

The validation activities include durability for both the engine and whole vehicle, environmental compatibility and sunlight simulation, high speed stability, aerodynamics, noise and vibration, and driving dynamics. More than 120 individual tests in all cover everything from the quality of the surface finish of the gold “organ stop” ventilation controls to the new W12 engine hardware and software.  Over 58 weeks of vehicle validation have been scheduled across  a pair of pre-series cars – Batur Convertible Car Zero and the Batur Convertible Engineering Car.

The real-world testing campaign started with an extensive 3,000 kilometre , five-country drive across Europe to simulate real world conditions. The route left Germany and travelled through Italy, France and Spain, across mountains, highways and cities, with the cars pausing briefly for an afternoon in Monaco for photography before continuing their journey to Idiada in Spain, where high speed testing will begin on private test tracks.

Paul Williams, Chief Technical Officer for Mulliner, comments:
“The purpose of an engineering validation public road drive is to test a vehicle's performance, safety, and reliability under real-world conditions. It allows our engineers to assess how the vehicle operates in a variety of environments, traffic scenarios, and weather conditions that cannot be fully replicated in controlled testing environments. This stage is critical for identifying potential issues, validating system integration, and ensuring the vehicle meets regulatory standards and customer expectations as part of the engineering development test program. At the start of the project it was clear that this car had to be the ultimate open-air Grand Tourer and so every element from the exterior design, engine power and hand-crafted interior has been created without compromise.”

At the proving grounds, the Batur Convertibles will begin seven weeks of durability work on handling tracks, mixed road conditions, high speed testing and abusive surface conditions. During all of these activities data and feedback are collated ensuring the technical targets are being met.

The Final W12 Grand Tourer

The Batur Convertible furthers the innovative design DNA introduced by its coupe sibling that will ultimately guide the design of Bentley’s future cars.

Created by Mulliner, the Batur Convertible follows the exquisitely hand-crafted Bacalar barchetta and Batur coupe. With the Batur Convertible, Mulliner continues its long tradition of crafting truly individual cars, tailored to the wishes of each of its extraordinary clients.

The Batur Convertible retains the most powerful version of Bentley’s iconic W12, with a 750 PS, hand-assembled 6.0-litre twin-turbocharged engine that has metaphorically and literally powered Bentley’s success for the last two decades. The Batur Convertible will be the last ever Bentley to use this incredible powertrain.

The convertible roof delivers an aesthetic of beauty as a modern, tactile alternative to a hardtop roof. A combination of insulation material, sealing system refinements and acoustic treatments create a cossetting environment in a system which can be deployed or stowed in just 19 seconds, with the car travelling at speeds of up to 30 mph (50 km/h), transforming the car from a luxurious coupe into an open-top Grand Tourer at the touch of a button.

Mulliner’s in-house design team will help co-create every Batur Convertible with its customer, working together through a specially created Mulliner visualiser that allows any part of the car to be customised in colour and surface finish. Endless samples of unique materials bring texture to the process, and the resulting designs will be truly individual and created by the customer – limited only by their imagination.

Batur Convertible Car Zero

Like all Mulliner Coachbuilt vehicles, the Batur Convertible is infinitely customisable – with each customer able to specify the colour and finish of literally every single surface of both the exterior and cabin of the car.

The engineering development car – Batur Convertible Car Zero – has had the same level of attention to detail as a customer’s own specification. The exterior paintwork is a bespoke colour – Vermillion Gloss over Vermillion Satin Duo tone – that provides a vibrant colour across the contemporary surfaces. The bodywork is underscored by front splitters, side skirts and rear diffuser in high gloss carbon fibre.

The front of the car features a grille of exceptional art – with the main matrix finished in Gloss Dark Titanium, accented with contrast chevrons in a horizontal ombré pattern that flows from Beluga in the centre and lighten to the vibrant sides in Vermillion Gloss. The “endless bonnet” line is finished in Gloss Dark Titanium paint, as are the 22” wheels – with the spokes in Gloss and Satin Black Titanium with Vermillion Gloss accents.

The second development car – known simply as the ‘Engineering Car’, features an entirely different specification. Midnight Emerald exterior paintwork is finished with a high gloss carbon fibre body kit and Satin Dark Titanium finished bonnet brightware and lower bumper meshes The wheels are tri-tone – with a Satin Dark Titanium body, gloss Porpoise accent faces and gloss Mandarin pinstripe. The same combination of Satin Dark Titanium and Mandarin is joined by gloss Beluga for the three-colour ombré fade to the front grille. The cabin echoes the exterior, with Cumbrian Green and Porpoises leather being accented with Mandarin stitching and piping, complemented with machined titanium Organ Stops and Bullseye vents. The veneer is Mulliner’s exquisite “guitar fade”, where the colour across the width of the cabin changes gradually from gloss Beluga, to high gloss carbon fibre, and back to gloss Beluga, and finished with a laser-etched audio signature of the W12 engine.