Mercedes-Benz will unveil the Vision Grand Sports Tourer at the North American International Auto Show in Detroit next month.

Series production development of this Mercedes model has already reached an extremely advanced stage and US reports indicate this, the first of a new line of 'R-class' vehicles, will be the second model line to be built alongside the M-class at the company's Alabama plant.

"We believe that the concept offers enormous potential for the launch of a new Mercedes model family", said Jürgen Hubbert, head of the Mercedes Car Group.

The so-called concept accommodates up to six occupants in individual seats in a luxury cabin and has a newly developed diesel hybrid powerplant which develops 234 kW.

First unveiled by Mercedes-Benz in 2002, the Grand Sports Tourer is said to combine the best features of touring saloon, van, estate and sport utility vehicles. It is an all-new interpretation of the "touring car", its creator claims.

A large panoramic glass roof stretches practically the entire distance between the windscreen and the rear end, bathing the interior in light. The centre consoles between the individual rear seats feature extra stowage compartments as well as large drinks holders for cups or bottles.

Separate DVD/CD players for the second and third seat rows, complete with headphones, allow the rear passengers to enjoy their own entertainment. The colour displays are built into the rear of the front head restraints and the rear centre console.

The four rear seats can be folded individually to create up to 2030 litres of luggage space (according to the VDA measuring method), which is substantially more than a conventional luxury estate can offer. In addition, the flat load compartment floor and the large tailgate make loading and unloading a great deal easier.

As in the BMW 7-series, the conventional automatic selector lever on the centre console is replaced by a lever on the steering column and control buttons on the steering wheel.

Mercedes says that, in models such as the Grand Sports Tourer, the electric motor is set to become an indispensable companion to the diesel engine, since it helps to further reduce fuel consumption and emissions without compromising on agility, comfort and driving enjoyment.

The concept's hybrid consists of a V8 diesel engine with 184 kW/250 hp from the S-Class and a 50kW electric motor, giving a total 234 kW of total power and 860 Nm of torque and the claimed acceleration of a sports car - it can sprint from zero to 100 km/h (62mph) in just 6.6 seconds. The top speed is electronically limited to 250 km/h.

The diesel hybrid system's claimed fuel consumption is according to the American measurement method and future engine generations will offer the potential for 33 mpg. In the European driving cycle, the Vision Grand Sports Tourer with a hybrid drive uses about 20% less fuel than a comparable diesel model.

Electronically controlled distribution of the workload between the diesel engine and the electric motor enables the benefits of both drive concepts to be used to the full: the electric motor kicks in when starting off, parking, driving in stop-and-go traffic or crawling in heavy traffic when less power is required, thus ensuring zero-emission motoring. The V8 is called into play when more horses are required while, during braking, the electric motor acts as a generator and produces current for recharging the drive battery.

The Vision Grand Sports Tourer is also the first hybrid so far with permanent all-wheel drive.

The concept also includes ride quality-nobbling 21-inch wheels that do however look great on a motor show stand, large, perforated brake discs and Mercedes' AIRMATIC air suspension.