Announced in 2015, the development of Rolls-Royce’s first “high-sided, all-terrain” vehicle — ergo, SUV — has reached advanced stages. This week our spy caught not one, but two prototypes undergoing testing in Germany.

Based on Rolls-Royce’s upcoming new aluminium architecture, which will also underpin the eighth-generation Phantom saloon, the Cullinan (as it’s code-named) is expected to go on sale in 2018. However, it will be preceded by the Phantom.

Engine options have not been announced but we fully expect the V12 to continue service, with a plug-in hybrid version likely to be added to the line-up at a later date.

Dimension-wise, it will naturally be much shorter than the new flagship Phantom limousine. However, the boxy appearance of the test mule is likely to be retained in the production version.

Rolls-Royce also promises genuine off-road ability in the Cullinan and claims a supreme ride quality no matter what terrain. Given how terrific rival Bentley’s Bentayga is to drive, the Cullinan will have to be an exceptionally engineered vehicle to better it.