BIG is indeed beautiful as discovered on his test drives of the new Jeep Cherokee and Grand Cherokee models.

With a slight modicum of apprehension, I accepted the opportunity to try out a multitude of muscular American metal at Millbrook recently – and it ended up being well worth the visit to one of the UK’s principal proving grounds.

This high-security vehicle-testing complex, sprawled over several hectares of Bedfordshire countryside, had within its rolling acres an off-road basin, a test oval and a switchback circuit with inclines, blind bends and testing curves, an ideal environment for the enthusiastic driver.

Casting my eye over Dodge, Chrysler and Jeep’s latest models with the appetite of a kid on Christmas Day, I tested as many as I could get my hands on – including the Chrysler Crossfire, Jeep Grand Cherokee and the awesome SRT-10.

First among Uncle Sam’s offerings, was the Jeep Cherokee CRD Sport model – visually it is little different from the previous model, albeit it had a visual refinement in 2004 with smarter front indicators and redesigned bumpers which has been retained, along with a list of standard equipment which includes smart 'Mechanica’ alloys, electronic heated door mirrors, tinted glass and the now-ubiquitous air conditioning.

I took it for a crack at the off-road course, an ochre-coloured mud bowl with differing consistencies of churned-up clay, concrete, railway-sleepers and the like.

This being my first time piloting a four-wheel drive of any description, I climbed into the vehicle and stared up at the first steep incline with trepidation...

The gutsy diesel engine was in fact a revelation; the Cherokee ate up the muddy inclines and clambered down the seemingly-perilous downhill sections with ease; the 2.8 litre unit providing acres of engine braking and torque every time you shifted up or down on the five-speed automatic gearbox.

Mated to the full-time Selec-Trac four-wheel-drive system, it made short work of a very muddy course.

In fact, at one point I mentioned to the Jeep representative that this was such an easy drive that I bet it was possible to manoeuvre it with one finger on the wheel... and this I duly did for a moment, with assistance from the generous power steering.

He also swore that I’d done this kind of thing before (drive a vehicle off-road that is) and it is probably more a testament to the Jeep’s ease of use than any competence on my part that I had to reiterate several times that I’d never off-roaded before! (Caution: I did have to press quite hard on the steering wheel with my index finger all the same – so, kids, don’t try this at home.)

The only caveat I would offer is, if you are a first-time off-road user, you would need to familiarise yourself with the low-ratio gear box as, at first, I had to frequently look down and remind myself which gear to use.

Although I suspect the average Jeep user will spend their three or four years with the car without ever visiting a muddy kerb, never mind clambering up a vertiginous fell in the Lake District...

The interior is smart and well-laid out; with a more car-like feel than before; with circular air vents and aluminium-effect panels around the cabin.

Useful cubby holes and drinks holders are also on hand, as is the standard CD player; it is certainly a long way removed from the creature comforts offered by the original wartime Jeep that was parked alongside its present-day brethren (the sum of said delights essentially amounted to a canvas roof and side-mounted spade; while you had to make your own music in those days.)

I also tested the Grand Cherokee 3.0 CRD Limited, which is a handsome-looking vehicle now that it has had a facelift which gives the front a pair of twin headlamps set in a smart indicator cluster on each corner.

Being a step-up in size and class from the Cherokee, it has a wood-trimmed cabin with a sat-nav console and leather interior as standard, in addition to all the usual Jeep accoutrements on the equipment list, most of which you would also find on the Cherokee.

It also features the next-generation Quadra Drive 2 - an active full-time, electronically-engaged clutch pack coupling in centre differential and front and rear variable locking Electronic Limited-Slip Differential.

Whatever that means, but it covered the muddy acres with an effortlessness similar to the Cherokee - although I did find the Cherokee with its simpler low-ratio box easier and more intuitive to pilot around the terrain.

Again, I doubt that the majority of the average Grand Cherokee’s life would be spent tackling anything more demanding than an icy front driveway - especially if you plump for the SRT-8 version; which has an exterior body kit which makes the vehicle more at home on an LA rapper’s music film set than a rural English country lane with its lowered bumper extensions, gigantic 20-inch low-profile alloys and a beefed-up engine which roars to the 62mph mark in less time than it says to tell the following sentence: 152 miles an hour.

Which is also its top speed. (Five seconds by the way, in case you ask.) You could only test the vehicle on the road circuits, which tells its own story.