THE first member of the Bentley Mulliner Coachbuilt portfolio - the Bacalar - has started its final test, development and durability work ahead of the build of 12 pre-sold customer cars due to start build next year.

Bacalar Car Zero, a purpose-built engineering prototype and the first barchetta-style - or open top - Bentley of the modern era, is already accumulating mileage and passing quality tests at a variety of locations around Europe.

The on-car validation programmes have been condensed into s 20 week schedule.

The car - the most expensive production Bentley and priced at some £1.8 million - includes a total of more than 750 new components, all of which have to pass Bentley's stringent quality, functionality and durability standards.

More than 40 of those parts are crafted in carbon fibre, while a complement of nearly 100 are produced using rapid additive manufacture techniques.

Bentley's director of Mulliner, Paul Williams, said: "Bacalar Car Zero is the crucial prototype that we're using to sign-off the design, engineering and craftsmanship of this ground-breaking part of Bentley Mulliner's future.

"The Bacalar is a thoroughly modern iteration of the coachbuilt Bentleys of the past - extremely rare, entirely hand-crafted, totally bespoke to each customer and exquisite in its details.

Just 12 examples are being created, guaranteeing rarity and exclusivity, and offering supreme luxury and breath-taking performance.

Each model will be handcrafted in Bentley Mulliner's workshop in Crewe, according to the individual customer's personal requirements.

The car is named after Laguna Bacalar in Mexico's Yucatan peninsula and continues Bentley's strategy of naming cars after remarkable landmarks which started with Bentayga in 2015. The Bentayga takes its name from a rock formation found on Gran Canaria in the Canary Islands.

Bentley Mulliner has an illustrious history and can trace its roots back to the 1500s when the company's original focus was customising luxurious, horse-drawn carriages.

The Bacalar features an enhanced version of Bentley's 6.0-litre, W12 TSI engine developing 650 bhp and is fitted with an advanced active all-wheel-drive system which varies the torque split between front and rear wheels.

The set up allows the Bacalar to use rear-wheel drive as much as possible during normal driving for optimum efficiency and dynamic performance.

The Bacalar is the first model from the Bentley Mulliner Coachbuilt portfolio - one of three divisions of the Bentley Mulliner organisation alongside Classic which is to deliver the Blower Continuation Series and Collections, responsible for the Continental GT Mulliner coupe and convertible.

It is a genuine ‘roofless' Barchetta - a luxury, two-seat, open-air performance car, the likes of which have never been seen before and the Bacalar shares no body panel with any other car in the Bentley line-up.

Bentley says it takes inspiration from the dramatic EXP 100 GT concept car conceived to mark the company's centenary in 2019.

The Bacalar shares only one exterior component with another Bentley - its door handle which is from the Continental GT and simply because it contains the keyless entry system.