Work continues on the Rolls-Royce Cullinan as spy photographers have captured another mule undergoing cold weather testing.

Set to battle the Bentley Bentayga, the Cullinan is a "high-sided, all-terrain motor car" that promises to become one of the most luxurious crossovers ever created.

The mule doesn't reveal much about the model's design but the company has previously said the Cullinan will have "exceptional presence, elegance, and purpose."  That's pretty vague but Rolls-Royce design director Giles Taylor has previously hinted the crossover will likely have coach doors as he believes they help to distinguish Rolls-Royce from other automakers.

Rolls-Royce has been slowly releasing details about the model and the company has already confirmed the crossover will ride on an all-new aluminum space-frame architecture that will underpin all future models starting in early 2018.  The Cullinan will also be equipped with a unique suspension that promises to deliver a “magic-carpet” ride regardless of whether you're traveling on the streets of Hollywood or the sand dunes outside of Dubai.

Little else is known about the crossover but previous reports have suggested it will be powered by a familiar 6.75-liter V12 engine.  The model is also expected to use an all-wheel-drive system that borrows components from the BMW X7.

Gallery: Rolls-Royce Cullinan mule spied cold weather testing

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