The luxury of a Rolls-Royce in a vehicle that can cross any terrain.

In its open letter on 18 February, luxury car maker Rolls-Royce Motor Cars gave an undertaking to inform stakeholders of the progress of Project Cullinan  that serves as a testbed for the company’s upcoming ultra-luxury SUV to do battle with the upcoming Bentley Bentayga.

Rolls-Royce is racing into the luxury SUV space because the competition is increasing. Bentley is to launch its first premium off-roader, the Bentayga, in 2016 and aware of the threat, Land Rover unveiled this year at the New York International Auto Show, the SVAutobiography, its most powerful, luxurious, expensive and exclusive Range Rover in history.

Rolls-Royce is refusing to refer to the car as a Sports Utility Vehicle and described it solely as a high-sided vehicle.

Keeping this promise, Rolls-Royce Motor Cars has published photographs depicting the first key milestone in the vehicle’s development programme. The photographs are of the first engineering mule, which will be seen on public roads this week.

This early engineering mule, based on a shortened Phantom Series II body, which is also expected to be shared  with the imminent BMW X7, has been created purely to begin the development of an all-wheel drive suspension system that will deliver a ride that will be effortless … everywhere. The body may hint at the size of the new car, but it features no design aspects of the eventual high-sided, all-terrain motor car announced by Rolls-Royce Motor Cars in February this year.

The mule rides on the first iteration of an all-new suspension that will assist Rolls-Royce engineers in developing a final all-wheel drive system that delivers Rolls-Royce’s hallmark “magic-carpet” ride not only on the road, but off-road too.

The first series of tests will focus on Project Cullinan’s on-road behaviour from suspension throw to high-bodied stability, and will test the new suspension across all types of international road surface specification at test facilities, as well as on public roads.

Test surfaces for the Project Cullinan will include: Belgian Pavé, cobblestones, corrugated concrete, noise development and measurement surfaces, resonance road, and acceleration bumps.

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.