GENEVA MOTOR SHOW: Mercedes-AMG slams down G 63

The new Mercedes-Benz G-Class seemed to have everything it needed for a new generation of off-roading when it was launched in G 500 form at last month's Detroit motor show.

But when the engineers at AMG looked at the G 500, they saw it needed more. More power, more torque, more grip, more speed and more cost.

And more side pipes. Big side pipes. Big, chrome-tipped side pipes exiting right underneath the rear doors. Subtle it ain't.

Less visually successful is the awkward massaging of the flat-looking GT Coupe's grille philosophy into the vertical-looking G-Class's nose.

The vertical slats of the GT's grille, reflecting Benz's Panamericana successes, serve mainly to make the G 63 AMG look even more vertical, while bending the grille out slightly at the bottom just looks strange.

As night follows day, a new AMG has followed quickly behind the donor model from Mercedes-Benz. Except it's not that simple this time around, with AMG involved in the G-Class's development from its earliest sketches.

The G 63 AMG looked to have been given the full treatment, with AMG CEO Tobias Moers determined to protect his company's phenomenal percentage of the outgoing model's mix.

It will arrive at next month's Geneva show with a 430kW version of AMG's biturbo 4.0-litre petrol V8 - a variant of the high-performance powerplant from the GT coupe.

It will mate this with a version of Benz's nine-speed automatic transmission, tweaked by AMG for faster, crisper gearshifts with double de-clutching in Sport and Sport+ modes.

Its multi-plate clutch centre differential has been programed to make the car behave as more of a rear-driver, with 60 per cent of the torque directed to the rear axle.

It retains the core G-Class layout, with front, centre and rear lockable differential buttons in the centre of the dash, even if it no longer has three lockable diffs.

AMG insists it sort-of does, because pushing the centre-differential button on the dash effectively locks the multi-plate centre diff anyway. The front and rear diffs continue to lock with dog clutches and it can all be done on the move in either low or high range.

Where AMGs have traditionally accepted and worked with the hardware Benz has given them, those days have gone.

It was Moers who insisted the core G-Class models adopt a fully independent front suspension, primarily so that his G 63 could behave the way AMG drivers expect. (And not, pointedly, in the way the old G 63 handled, which it did only sporadically.)

In a case of "you want it, you got it", Moers insistence left AMG responsible for both the suspension design and development of the entire G-Class range.

He's left the ladder-frame chassis with four longitudinal control arms per side for the solid rear axle and included a strut tower brace under the bonnet.

He also added an electromechanical power steering system, ridding the world of the last recirculating ball system in widespread production.

It takes the double-wishbone independent front suspension and adds its own ride control suspension, with active adaptive damping. It adds wheels of up to 22 inches, slotted beneath fattened wheel-arches and hiding bigger brakes.

Benz claims the new car scores 13.2L/100km on the NEDC cycle (for 299g/km of CO2). The G 63 uses cylinder deactivation to reach even those modest figures, but the current G 63 AMG sales suggests its customer base cares not a jot for such things.

The entire beast is motivated by a 4.0-litre V8, complete with a pair of twin-scroll turbochargers mounted inside its vee angle. And the current G 63 AMG suggests its customer base cares quite a lot for such things.

Like the rest of the AMG range, the new '63' motor has been pulled down from the old 5.5-litre biturbo V8 which is supposed to give benefits in weight and packaging, but not cost.

Sure, it's shrunk, but it's no shrinking violet, punching out 850Nm of torque from 2500rpm and holding it to 3500.

Benz claims the G 63 AMG will hit 100km/h in 4.5 seconds and stretches up to a 220km/h top speed (a point at which the old one's front wheels tried to leave the ground).

The AMG Driver's Package lifts that to 240km/h, a point at which it's pushing more air than an elephant in a Heinz factory.

"The new AMG G 63 brings driving performance to the segment of unadulterated off-road vehicles in unexpected form," Moers insisted.

"It was important for us to tie in with the original character on account of the cult status the G 63 enjoys with our customers and fans.

"The vehicle has nevertheless reached a completely new dimension in terms of technology with the 4.0-litre V8 biturbo engine as well as in combination with the off-road characteristics, the agility and the vehicle dynamics achieved.

"This applies to the entire G-Class model series. Mercedes-AMG is responsible for their suspension and chassis development as well as V8 competence."

AMG also claims the G 63 is even better off road than its predecessor, with a 2.93:1 reduction gear for low range (up from 2.1:1) and it can be switched into low range at up to 40km/h or back to high range again at up to 70km/h.

Its rear suspension can compress up to 82mm in demanding off-road conditions and droop up to 142mm, while the G 63 totes 241mm of ground clearance. It also has Sand, Rock and Trail off-road modes built into its push-button driving systems.

It's a bigger car than it was before, too, with 101mm added to the overall length, another 121mm added to its width and it's now 40mm higher.

The added space inside gives it 150mm more rear legroom, another 38mm of front legroom, 38mm more front shoulder room and 68mm more front elbow room.

Expect the new G 63 to arrive in Australia, where AMG versions account for 60 per cent of current G-Class sales, in the second half of this year -- priced around the outgoing model’s $235,000.

It will be followed by the diesel version -- priced close to the existing G 350d model's $165,000 price tag -- by the end of this year.