Spied: Rolls-Royce's Project Cullinan SUV

Rolls-Royce has begun development of a new utility vehicle.

Rolls-Royce has commenced real-world testing of its upcoming utility model. Referred to as a "high-sided, all-terrain motor car,” the Roller SUV, which is being developed under the codename Cullinan, which eventually take on Bentley's Bentayga.

As confirmed by the British automaker in April, Project Cullinan is being developed on a modified version of the Phantom Series II sedan. The engineering mule features a shorter wheelbase than the Phantom and also sports a noticeably higher ride height. Although the mule doesn't provides any styling hints for the upcoming SUV, it does at least give us some idea of how big the final product will be.

Cullinan will be based on an all-new aluminum platform that will also make use of lightweight aluminum body panels. What engine might power the SUV remains a mystery, but a V12 is in the running. Rolls-Royce might also opt to use a more efficient turbocharged V8.

Engineers are currently testing the mule of smooth pavement, but the SUV will eventually be put through its off-road paces.

"Project Cullinan engineering mules will spend equal amounts of time testing on-road and off-road to ensure that the customer will experience the same unrivalled ride quality on loose surfaces and challenging terrain as they do on the road today,” the company said in a previous statement.

Rolls' Bentayga rival isn't expect to hit the road until at least 2018.

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