Bentley Bacalar shown testing ahead of 2021 launch

New pictures of the Bentley Mulliner Bacalar have been released showing a prototype testing on British roads ahead of its launch next year.

Unveiled at the beginning of this year, the open-cockpit Bacalar was created by the car-maker's bespoke Bentley Mulliner division to rival cars like the Aston Martin V12 Speedster and the McLaren Elva.

Announcing it would make just 12 examples, with all of them already spoken for, Bentley said each Bacalar would cost an incredible £1.5 million ($A2.7m) plus taxes.

Despite such a small run of cars, Bentley says it is committed to putting the Bacalar through its rigorous testing and durability program ahead of its 2021 launch which includes proving it is capable of exceeding 200mph (322km/h).

According to engineers, as well as a top-speed run, high-speed stability and handling of the fast Bentley have already been signed off for the production car.

The prototype must now accumulate tens of thousands of kilometres while enduring tortuous durability tests. Finally, the car will be tested at temperatures up to 80C Celsius before being approved for production.

Heavily inspired by the Bentley EXP 100 GT concept that was designed alongside the Bacalar, the roofless production car borrows its unusual name from a lake in Mexico.

Created in isolation of Bentley's mainstream models, only the platform, powertrain and door handles have been carried over from the Bentley Continental GT convertible on which the Bacalar is based.

It’s made almost entirely of carbon-fibre and features crisp, dramatic lines, a centre-spline bonnet and single oval headlights that look like they’re lifted directly from the concept.

Instead of the EXP’s all-electric battery and motors, the Bentley Bacalar is powered by a twin-turbocharged 6.0-litre W12 that has had its power boosted by 19kW to a towering 485kW.

The standard Bentley Continental GT’s 900Nm peak torque remains unchanged and, against the clock, the special-edition hits 100km/h from standstill in 3.6 seconds before eventually topping out at 330km/h.

Helping owners specify their cars, Bentley has released six example specifications that are claimed to each demonstrate a different personality and purpose, but also reflect just what's possible to order through Bentley's bespoke Mulliner division.

According to the designers who created it, the Bentley Bacalar was the ideal opportunity to explore what a modern Bentley should look like in the future.

Surprisingly, that explains the vibrant Flame Yellow hue and the switch from traditional chrome to cool anodised bronze trim.

Inside, again, the designers and engineers decided to push the envelope.

Claimed to pay tribute to the late 1920s Birkin Bentley, the wraparound open-cockpit cabin is said to recapture the blustery atmosphere of the original.

And that included making the Bentley Bacalar strictly a two-seater. Where you would expect to find the rear pews there’s dedicated space for a set of bespoke luggage.

Considering its towering price tag, the level of craftsmanship is outstanding. The seats, for example, requires 148,199 stitches for its unique quilted finish.

Where you might expect to find heavily lacquered wood is untreated open-pore river wood from 5000-year-old naturally-felled timber, while the finest leather is employed and anodised titanium finish applied on the minor controls.

Perhaps most surprisingly, considering the car was designed and developed in the UK, the million-dollar roadster has no roof.

Bentley claims its owners will only ever use their Bacalar on fair-weather days, which is a good thing since its interior isn’t the least bit water-resistant.

Sadly, none of the 12 cars made are destined for Australia.