Mercedes F700

OUR drive of the Flying Spur proves how effective Bentley’s approach to luxury motoring is. But if Mercedes has its way, things could soon be very different at the top of the car market.

The German company’s vision of the future in this class is based on a 1.8-litre four-cylinder petrol engine. We’ve tried it here in the F700 research saloon, but it could make its production debut in the next-generation S-Class, due in 2011.

Mercedes claims that the Diesotto unit combines the best of both worlds. It can spark-ignite fuel like a petrol powerplant and auto-ignite it by compression, as a diesel engine does. The result is the kind of fuel economy and torque figures usually associated with an oil-burner, as well as the refinement of a petrol unit.

What’s more, by using an electric motor instead of a flywheel, the engine can be stopped and restarted instantaneously, further boosting fuel returns.

The Diesotto powerplant offers 238bhp and 400Nm of torque, but has CO2 emissions of only 127g/km and returns over 40mpg.

From behind the wheel the engine is a revelation. It powers the 2.2-tonne luxury prototype with ease.

Other F700 innovations that could grace the S-Class include suspension linked to lasers which scan the road. Data from these is used to adjust each wheel automatically so the ride is as smooth as possible.