Innovation can be a double edged sword. For every Audi Quattro, Toyota Prius or Renault Scenic there are the Jensen FFs, Honda Insights and Nissan Prairies - cars that were first to market but never quite captured the public's imagination in the same fashion. Latterly it has been French manufacturers who have seemed most willing to embrace new market niches, but Mercedes-Benz, traditionally one of the more conservative companies, have something to make all of us sit up and take notice in the R-Class Grand Sports Tourer.

The top brass at Mercedes noted that while many of their customers liked the space and utility of cars like the M-Class 4x4, they didn't much care for the ride quality or the handling that is inherent in any dual-purpose vehicle. What if the stance and road manners of a luxury saloon could be combined with the versatility of a 4x4 or an MPV-style vehicle? That's the reasoning behind the R-Class, but it has some significant hurdles to overcome.

It's estimated that at least 60 per cent of all R-Class sales will come from the US, a motoring culture that has traditionally seen anything without a boot as being only good for shopping, picking up kids or rock hopping. This culture is slowly changing with the advent of high end SUV sports utility vehicles but the R-Class boldly teases this development in a new direction. Wealthy private customers with growing families have found their needs unmet by saloon cars or rather frumpy MPVs. The social stigma that increasingly surrounds big 4x4 vehicles has opened the way for a vehicle like the R-Class but will it prove a hit, miss or maybe?

Priced from just under £40,000 and measuring fully 5,157mm from nose to tail in long wheelbase form, there's nothing apologetic about the R-Class. In fact, it's even longer than an S-Class limousine but offers space for upto seven inside with around 64 per cent of the vehicle's body length available for its occupants. Think of the long bonnet and boot of a saloon car in this class and you begin to appreciate that Mercedes may be on to something here.

"The R-Class is a seriously imposing slice of Stuttgart real estate"

Take seat spacing as a for instance. This is the sort of vehicle designed for customers who aren't accustomed to flying economy. The acid test for a vehicle with three rows of seats is the space from the second to third which in this case is up to 920mm. Moreover, the seats in the middle row can slide individually fore and aft, thereby increasing the seat spacing to as much as 990mm. No longer are the rear seats only suitable for the kids. Despite the swooping roofline, up to 1,027mm of rear headroom is available. The rearmost rows of seats also fold flat into the floor allowing the load capacity to expand to a massive 2,057 litres. Try finding an estate car that can match that. Short wheelbase derivatives are also offered where there's a choice of five or seven seats. The five seat versions ditch the rear row in favour of a larger boot but sacrificing two berths really diminishes the vehicle's practicality.

A number of enticing options are offered, such as the remote control open and close function for the tailgate, the Luxury Climate Control with over a dozen sensors and a separate air-conditioning unit for the third row of seats. A separate DVD/CD player for the rear and a panoramic sunroof will also make you very popular with the offspring. The R-Class isn't all about the expensive options, however, and all models feature a very extensive standard equipment list.

Engine outputs range from 190bhp up to 388bhp, the V8 powerplant under the bonnet of the R500 propels it from standstill to 60 mph in just 6.3 seconds and on to an artificially limited top speed of 155mph. Also to be found in the engine line-up are two six-cylinder diesel power units with advanced common-rail, direct-injection technology, whose credentials include improved fuel consumption, even lower exhaust emissions and an audible improvement in refinement. The larger V6 oil-burning engine places its class-beating peak torque of 510Nm on tap from as low down as 1,600rpm. The average fuel consumption figures returned by the R320 CDI are no less astounding: 30.4 mpg. The smaller 2.8-litre CDI diesel forms the entry-point to the range with 440Nm and fractionally better economy of 30.7mpg.

All engine models are partnered as standard by the 7G-TRONIC seven-speed automatic transmission, which itself comes with an interesting feature in the form of Direct Select. This electronic transmission control system has allowed Mercedes engineers to dispense with the conventional automatic selector lever in the centre console and to replace it instead with a lever on the steering column. Additional gearshift buttons on the steering wheel enable drivers to manually pre-select the seven forward gears, just like in a Formula One racing car. This allows the power reserves of the six and eight-cylinder engines to be harnessed to optimum effect in any driving situation.

Permanent all-wheel drive, the electronically controlled 4ETS traction system and ESP team up to offer peerless driving safety and keep the new R-Class safely on course, even in very bad road conditions. These systems all make up part of the vehicle's standard specification, as does air suspension at the rear axle.

Although there aren't too many letters of the alphabet left for Mercedes to exploit, if the R-Class is anything to go by, the brains at Stuttgart will continue to sniff out new market niches worth plundering. The jury's still out on whether this vehicle will be a success or a failure but it's a bold move that merits the plaudits.

TOP 5 R CLASS DEALS

The results below show the top R CLASS deals on buyacar

	Mercedes-benz R Class R320 CDI SE 5dr [AMGBodykit] [7 Seat] Auto Tourer Estate
	ETR	Mthly £677	Saving £3,284	Price £37,486
	Mercedes-benz R Class R280 CDI SE 5dr [AMG Bodykit] Auto Tourer Estate
	ETR	Mthly £611	Saving £2,951	Price £34,119
	Mercedes-benz R Class R320 CDI Sport 5dr [AMG Bodykit] [7 Seat] Auto Tourer Estate
	ETR	Mthly £708	Saving £3,419	Price £38,851
	Mercedes-benz R Class R320 CDI Sport 5dr [AMG Bodykit] Auto Tourer Estate
	ETR	Mthly £689	Saving £3,329	Price £37,941
	Mercedes-benz R Class R320 CDI SE 5dr [AMG Bodykit] Auto Tourer Estate
	ETR	Mthly £658	Saving £3,194	Price £36,576

typical 9.63% APR

PCP finance quote over 48 months,  10,000 miles pa,  deposit of £1000