GENEVA MOTOR SHOW: Mercedes-Benz G 500 AMG 4X4²

Mercedes-Benz is calling the most radical G-Wagen in its history a show car – but that’s what it said about the G 63 AMG 6X6 as well.

There are few doubts that some markets, particularly in the Middle East, are trying to drag Benz into building its high-riding, high-powered G 500 AMG 4X4² as a production car after its debut in Geneva on March 3.

And why not? The G 500 4X4² is effectively a G63 AMG 6X6 with a new engine, one axle left off and everything else stuffed into a five-door, long-wheelbase G-Class bodyshell.

It’s not as though the G 500 LWB lacks for off-road credibility, but the show car makes it look like a GLA.

For starters, it sits on the same portal axles as the radical 6X6, which raises its ground clearance from 250mm to 450mm at a stroke. They also help it to get a Benz rating to driver through a full metre of water, where the stock version tops out at 'just' 600mm.

Benz isn’t offering fuel economy, weight or performance data on its new toy, but it is confirming it will use AMG’s new 4.0-litre biturbo V8 instead of the bigger 5.5-litre biturbo V8 from its designated brother.

It’s enough to give the G 500 4X4² 310kW of power and plenty of torque at lower rpm (though, again, Benz isn’t saying exactly how much).

Given that this basic engine delivers another 65kW in GT S mode, it’s seems safe to say it’s had its torque curve modified for at least the sports car’s 700Nm from 1750rpm.

While it will lose the dry-sump lubrication system for off-road use, it will retain the hot-vee turbo configuration and the direct, spray-guided fuel-injection.

It will mate, as usual, to a seven-speed automatic transmission, largely because AMG already had a reinforced one ready to go from the 6X6. It also runs a transfer case, so there is high- and low- range on offer, too.

From there the G 500 4X4², with full-time four-wheel drive, gets tricky. There are three diffs controlling drive distribution beneath the G500 4X4² and all of them have push-button mechanical diff locks.

Pulled straight off the three-axle machine, the locking diffs are a good indication that the G 500 4X4² is designed for serious off-road work – but not the best indication.

For that, you need look no further than the wheel-arches, where two spring and damper modules sit at each corner. The first of them runs a fixed rate spring and damper, while the second uses an electronically variable damper to give it adjustable damping.

It means the G 500 4X4² always has a baseline level of ride and handling, but can switch between comfort and sport modes (in just 15 milliseconds) depending on the conditions.

If those conditions look like tough off-road work, you’ll be happy that it’s now got a 52-degree approach angle (up from the standard G 500’s 36 degrees), a 54-degree departure angle (up from 27 degrees) and an astonishing 47 degrees of ramp-over angle.

A lot of this added off-road ability comes down to sharing the same portal wheel hubs as the G 63 AMG 6X6, which means they’ve both pinched them off the Unimog.

Instead of just driving shafts from the front and rear diffs through to the middle of the wheels, it sends the shafts to cogs sitting in the top of a big hub-mounted casing.

Whenever you step on the throttle, it turns this cog, which in turn turns another cog beneath it, which then drives the wheel. Effectively, it just tucks everything out of the way and lifts the body high at a small cost to driveline efficiency.

While it shares the standard G 500’s overall length and 2850mm wheelbase, it tacks on size everywhere else. The track widths grow by 299mm to almost 2.1 metres. The height leaps to almost 2.5 metres – or even taller than the G 63 AMG 6X6.

The changes have forced AMG to tack on detachable carbon-fibre body parts to cover all of the mechanical bits and keep the G 500 4X4² legal.

One of the tough bits to keep covered are the G 500 4X4²’s wheels and tyres. The show car rides on unique 22-inch alloy wheels and runs on 325/55 R22 tyres, which don’t exactly sound in keeping with the rest of the machine’s off-road focus.

But there’s a fix, with an alternate set of boots on offer from AMG. The wheels might be smaller, at 18 inches, but the off-road size 37 x 12.5 x 18-inch MT rubber will get you more places, more of the time.

They’re also fitted to bead-locker rims, which keep the tyre wedded to the wheel rim even when the tyre pressures are dropped down to below 0.5 bar for sand work. Or, in a worst-case scenario, zero bar.

And if all of that height and ground clearance doesn’t save you, there are two stainless steel protective plates bolted to the bottom of the bodywork. One thing they don’t have to work hard to protect is the exhaust system, which feeds out to the sides, ahead of the rear wheels, instead of beneath the rear bumper.

Like the G 63 6X6, the G 500 4X4² doesn’t look like a hard-core bush-basher from inside. Instead, it looks like a very luxurious Mercedes-Benz.

It gets the Exclusive kit from AMG’s Designo line, which includes high-quality leather trim, diamond-quilted contrast stitching and every piece of luxury kit AMG already stuffs into the G 63.