When it first came to Britain nine years ago, the Jeep Grand Cherokee was a credible alternative to the Range Rover — then as now king of the 4x4s — at a price lower than the Land Rover Discovery’s. A lot has happened to SUVs since then. BMW, Mercedes, Porsche, Volvo and Volkswagen have entered the fray and the Range Rover and the Discovery are now superior new models.

So the new Grand Cherokee has a different task to perform. These vehicles no longer sell on their ability to cross deserts and mountain ranges but Jeep, like Land Rover, insists on making SUVs that can cope with extreme conditions: off-road supremacy is a badge of office. Even so, Jeep can’t afford to ignore the fact that today’s 4x4s need also to be as smooth as a premium saloon on normal roads.

For Jeep, there is a further complication: it is part of the DaimlerChrysler group, which also makes Mercedes. This means that the Grand Cherokee is destined to be an understudy for the new Mercedes ML, with which it shares its 3 litre V6 diesel engine.

But this is where the high-performance 5.7 litre petrol V8 Hemi engine comes in (“hemi” referring to the now-common hemispherical combustion chamber that is part of Chrysler’s heritage).

It represents something that Mercedes can’t offer: good old-fashioned American muscle.

The V8 produces 322bhp and propels the hefty Jeep to 60mph in 6.8sec and to a maximum of 130mph. A sharp prod on the throttle produces a wonderful roar that makes it seem even faster. And although it has a clever (and barely detectable) system for deactivating four of its eight cylinders when not required, such as cruising at low speed, it still drinks unleaded at an embarrassing rate. The official urban fuel consumption is 13.3mpg.

The car comes with satellite navigation, tyre-pressure monitoring, park assistance, automatic wipers and memory seats, all for £37,995, which happens to be the same list price as the Land Rover Discovery V8 S with a 295bhp engine — the Jeep’s direct competitor. The Disco is still the class leader, though the cheapest automatic version you can buy costs £33,490 and that will be undercut from July by the £29,495 Jeep 3.0 CRD.

Jeep devotees will notice improvements all round for the new model, although the boxier styling, with narrower windows and round headlamps, may not receive universal praise. Six inches longer and with a 2.5in wider track than its predecessor, the Grand Cherokee now has independent front suspension and rack-and-pinion steering, which make for a more comfortable ride and better on-road handling.

Cars for the UK market, which are assembled in Austria, all have Quadra-Trac II, the most advanced four-wheel-drive system Jeep has offered, with three electronically controlled differentials, low-range gears for mud-plugging, and electronic stability control.

Because it still has a rigid “live” axle at the rear, it is not able to soak up the bumps and uneven surfaces of British byways as well as the best of the competition, but the Grand Cherokee scores in quietness and refinement, making it a pleasant companion on a long journey. The new Mercedes diesel engine is, if anything, nicer in this application than in the ML, where it is combined with a fussy seven-speed automatic gearbox; all Grand Cherokees have a five-speed automatic.

The quality and general appearance of the interior is better than before but the combination of textures and colours marks it as American — the plastic mouldings are hard, the leather (grey or khaki) shiny, some of the fittings just a bit crude. The Grand Cherokee seats only five but a high floor and short seat cushion mean that the rear passengers (particularly the one at the centre) have a less comfortable time than those in the front.

Jeep has done what it had to do with its biggest and most expensive model: it is faster and sturdier than its predecessors. But SUVs have changed, and so have people’s reasons for buying them. The new Grand Cherokee may just be the right car at the wrong time.

VITAL STATISTICS

Model Jeep Grand Cherokee 5.7 Hemi Limited
Engine type Eight cylinders, 5654cc petrol
Power/Torque 322bhp @ 5000rpm, 369 lb ft @ 4000rpm
Transmission Five-speed automatic, four-wheel drive
Fuel/CO2 18.3 mpg (combined cycle), 366 g/km
Performance 0-60mph: 6.8sec / Top speed: 130mph
Price £37,995
Verdict Back to the future: an SUV with real American muscle
Rating 3/5

THE OPPOSITION

Model Porsche Cayenne S £43,738
For Faster than the Hemi. Porsche sports car heritage
Against Hard ride on the road and can’t match Jeep off it

Model Land Rover Discovery 3 V8 S £37,995
For Looks the business. Air suspension and brilliant Terrain Response Control
Against Seriously heavy, not close to Hemi performance