BENTLEY'S ‘ultimate' grand tourer, the coachbuilt Batur by Mulliner, has completed its whole vehicle development programme.

Work now commences on the build of customer cars, each of which will feature bespoke craftsmanship and take around four months to handcraft - with the last one to be completed at the end of next year.

Following on from the creation of two development vehicles - known as Car Zero and Car Zero-Zero - just 18 Batur customer cars will be produced by hand in the Mulliner workshops.

However, no concession has been made in Bentley's rigorous testing regime, which includes durability tests on handling tracks, real-world road conditions, high speed testing beyond 200mph, and rough surfaces.

Other tests included 600 hours of solar loading, equivalent to five years in an Arizona desert, to ensure that the sustainable materials used in the Batur's construction will be robust enough to endure a lifetime's use.

Car Zero was built to the same levels of craftsmanship as each of the 18 customer cars to come. Its bespoke exterior finish, Purple Sector, is complemented by front splitters, side skirts and rear diffuser in a high gloss natural fibre finish.

The main matrix grille in Gloss Dark Titanium is accented with contrast chevrons in a horizontal ombré pattern that flows from Purple Sector in the centre, gradually darkening to Black Crystal at the periphery. The ‘endless bonnet' line is finished in Satin Titanium, as are the 22-inch wheels which feature spokes in Gloss and Satin Black Crystal.

A second development Batur, Engineering Car Zero-Zero, is finished in the equally striking Marina Teal finish. The bespoke finishes, and new components such as the one-off LED headlamp units, faced a series of tough durability tests, which included a 2,500 km European tour, high speed testing at closed circuits, and extended exposure to the harshest environments.

In total, over 800 one-off components have been tested and proved in 160 simultaneous weeks of intensive development work.

The W12 engine that powers Batur can trace its origins back to the Continental GT of 2003. It has continued to evolve, becoming more powerful, refined and efficient with each successive generation.

As Bentley begins its journey to full electrification, the Batur's W12 represents a celebration of this remarkable engine as well as its swansong.

Its 750ps peak output makes it the most powerful W12 and therefore the most powerful Bentley powertrain ever built. Its new air intake system, modified turbochargers, revised intercoolers and new calibrations for engine, transmission and electronic stability control were tested to the limit in over 100 weeks of powertrain development.

The engine's breath-taking performance is matched to the most advanced Bentley chassis specification ever.

Highlights include speed-tuned air suspension, electric active anti-roll control, an electronic limited slip differential, four-wheel steering and torque vectoring.

All 18 examples of Batur have already been reserved, and each customer can now continue the process of co-creation, guided by Mulliner's in-house design team.

After the customer specification of the colour and finish of almost every surface of the Batur, each car will be handcrafted in the coming months at Mulliner's workshop in Bentley's carbon neutral factory in Crewe, England, with each one taking around four months to complete.