Driven: Mercedes G63 AMG

As quantifiably bad as it is extremely cool, the 'new' twin-turbo G63 proves life really isn't fair, but Harris loves it all the same

Whatever else you do, just please, please don't try to be objective about the G63 AMG. In a normal world it wouldn't exist, but according to the twisted conditions of supply and demand in the midst of a global recession, people want this car. In fact they want it so badly that an AMG gaffer wasn't quite sure if the projected sales for this 2,550kg , 550hp, live-axle SUV wouldn't exceed those for last week's new AMG, the rather spiffing SL63.

Still 5.5 litres but a new engine and two turbos

Now in its 33rd year of production, the G-Class (it ceased being the G-Wagen in 1998) has been updated for 2012 with a new interior, some exterior tweaks and, in the case of the AMG variants, two apocalyptically silly new powertrain options. Replacing the old G55 Kompressor - largely because they'd run out of engines to bolt into the unsuspecting old shed - is the new bi-turbo, 5.5-litre V8 already starring in AMGs of the E, CLS, S and SL variety. This time it has 544hp and is limited to 560lb ft. Sitting above it is the newly elected crowning-star of silliness, the twin-turbo V12 G65 AMG. This offers 612hp and 737lb ft. The G63 is the only version available to test at this time. (And we won't be getting the G65 here, last we heard - Ed.)

Surprising, yet unsurprising
The G63 somehow manages simultaneously to be both the least surprising and most surprising vehicle I have driven in 2012. Everything you understand about it - the ancient body-on-frame construction, the immense power, the staggering 2,550kg mass for something that isn't actually that large - all confirms what is already known. Namely that this will re-adjust your perceptions of fast-truckdom. But even when mentally prepared for this you cannot fail to be astounded when you first get the chance to open the taps between 50 and 120mph. The engine and exhaust roar, the wind noise, the utter carnage of insect death on the vertical screen. It's madness. It's also addictive.

Facelift comprises ... er ... nope, not sure

The G63 is not a good car. It is a bad car - and it fulfils both meanings of that second adjective. On smooth German asphalt the ride is choppy and the moment you happen across a rare patch of broken surface the thing bucks around and generally reminds you that it was originally designed for the German military back in 1972, not to hustle along A-roads with a 544hp rocket up its jacksie. Of course there is immense fun to be had from cajoling speed from something that really shouldn't offer it, but that's where the fun ends on twisty roads in the G63.

This thing belongs on the autobahn or the city centre. Anything in between is no-man's-land for all the reasons you would expect. Especially the new ESP system, which calls time so early you think it's broken. Switch it off and it allows a nanosecond of bad behaviour before regaining control and, thanks Hal, switching itself on again.

It was once a hardcore off-roader...

Retro modern
I suppose we should be exasperated that one of the world's great off-road machines, and the only SUV of its type in Europe that can still be bought with individually locking front, centre and rear differentials, has been turned into an urban dragster. If you want to get muddy, Merc will sell you a G350 CDI. The G63 is the definitive look-at-me truck. It burbles through quad side-exit exhausts and each tickle of throttle releases vast quantities of noise into the atmosphere. I'm sure it's been tuned to make the best possible use of reflections and echoes from buildings.

Its traffic light sprinting credentials are impressive. Now fitted with the AMG Speedshift 7G-Tronic transmission, it launches itself with a little Yokohama chirp, monsters first gear then shifts quickly and smoothly into second, by which time it has recorded 5.4 seconds for the profoundly meaningless 0-62mph sprint. I did it time and again, and never became bored. The heaving, the squat, the prow rising, the noise - all of it makes for one of the great motoring events.

Bye bye Kompressor, hello Biturbo

Inside there's a new cabin consisting of almost entirely contemporary switchgear, but the basic architecture of the dash, and that passenger grab handle, remains the same. The G-Class is the only Mercedes to have a manual handbrake. It is also the only Mercedes to still use the roof-mounted grab handles from the 1970s W123 E-Class. I love these slightly botched cabins, there's endless fun spotting where stuff has come from, and it feels so well bolted together. From the way the doors clank shut to the luxurious paintwork, this might be the best-built car on sale. Which is madness for a supposedly shonky old hot-rod built in Austria.

The (daft) facts and figures
AMG claims a 13 per cent reduction in fuel consumption on account of the new seven-speed 'box and stop-start technology. I averaged 12mpg and wasn't being that badly behaved, but then people who spend €137,504 (around £122,000 when it lands here) don't really care about that - the 96-litre tank gives a half-reasonable range.

New grille, more vents, still a proper G

On the Autobahn, it's endlessly amusing, but only up to 131mph where a speed-limiter calls time. The G65 has its limiter raised to 144mph. It hits that enforced maximum with the same frustration as a bar-fly being held to a three-pint limit. I have no idea what it would manage in an unexpurgated state, but something near 160mph seems entirely reasonable. Stopping repeatedly from high speed didn't bring any fade from the 375mm and 330mm brakes - although on twisty stuff, braking hard into turns there can be a heart-jumping moment between pedal pushing and the electronic brain juggling brake force distribution and available grip. It always stops though. Eventually.

There is no earthly reason to buy this car, and for many that alone is the very reason to buy it. AMG already has over 300 orders for the LHD only, €264,180 G65 AMG, and it only sees its overall contribution to total G-Class sales increasing in 2012. In 2011, 40 per cent of all Gs were AMGs.

It's hard to deny that G63 sales are perhaps the ultimate barometer for the irresponsible use of wealth. But it is harder for those of us who love interesting machinery to deny that there is something undeniably appealing about this car - whereas the infinitely more capable BMW X6 M remains profoundly uncool. Why is that?

MERCEDES G63 AMG
Engine: 5,461cc V8, twin turbocharged
Transmission: 7-speed auto, all-wheel drive
Power (hp): 544@5,500rpm
Torque (lb ft): 560@2,000rpm
0-62mph: 5.4 sec
Top speed: 131mph
Weight: 2,550kg (LWB)
MPG: 16.8 (NEDC combined)
CO2: 322g/km
Price: £122,000 (est for UK)