Competing luxury carmakers are taking very different approaches to developing their forthcoming SUV models.

How do you make a luxury SUV stand out from the crowd? According to Bentley, the answer is to make it incredibly fast.

When its new off-roader rolls off the production line in 2016, it could well be capable of hitting 320 km/h. At least, according to reports, that's the challenge the company's engineering department has been set.

Making a sportscar that fast is difficult enough, but to achieve those levels of performance, safely, in a vehicle that could stand nearly 2 meters high and need massive ground clearance (to avoid rocks and potholes) would be some feat indeed. And, it would no doubt have potential buyers forming a neat and orderly line outside dealerships.

But while Bentley is focusing on the ‘S' for Sport, Rolls-Royce is getting obsessive about the ‘U' for Utility.

The BMW-owned luxury brand first admitted that it was loosely considering the idea of a rugged limousine in January. But unlike its closest direct competitor, it is in no rush to even develop a working concept.

Speaking to Autocar, Jolyon Nash, Rolls-Royce's global sales and marketing chief, said: "Sports and utility are not two words you normally associate with Rolls-Royce. The challenge we have given to our designers is a concept that fits Rolls-Royce."

And if the designs don't meet that goal then "we won't be entering the segment," Nash says.

The premium SUV market is growing quickly; until recently Range Rover and the Mercedes G-Wagon pretty much had the segment to themselves.

But in recent years Porsche and Audi have joined the party and now Lamborghini, Maserati, Bentley and Jaguar are all preparing to move into the segment, too. Rumours are even surrounding BMW, Rolls-Royce's parent company.

It is reported that the company is testing the feasibility of building a full-size luxury off-roader based on its 7-Series platform.