At next week's Geneva Motor Show, Brabus will reveal the 850 6.0 Biturbo Coupe. They claim it is the fastest and most powerful all-wheel-drive coupe in the world, and we do not wish to mess with it.

Brabus' new monster is of course, based on a Mercedes-Benz, specifically, the new S63 AMG Coupe with four-wheel-drive and a seven-speed automatic gearbox. But there are many crucial differences. First off, it's not a 5.5-litre V8 anymore.

No, Brabus has taken the 'standard' turbocharged AMG V8, bored out the cylinders and fitted larger forged pistons to make it a 5.9-litre V8. There's a special Brabus crankshaft, flow-optimised cylinder heads, and two new Brabus-spec turbochargers with larger compressor units and modified exhaust manifolds. Thanks to this last thing, many horsepowers happen.

Then there are 75mm-thick down pipes, and a full stainless steel sports exhaust system which should merrily chirrup the terror and hellfire of 838bhp and a full 848lb ft of torque - scaled down from a heady 1069lb ft in the "interest of the longevity of the entire powertrain". Yikes.

It'll go from 0-62mph in 3.5 seconds, go from 0-124mph in 9.4 seconds and top out at 217mph. Yet that top speed is limited, too... by the tyres.

You'll notice the carbon fibre spoiler, a carbon fibre rear diffuser, a boot spoiler, carbon fibre surrounds for the side air outlets, Brabus monoblock wheels - available from 18 to 22 inches - and much interior tweakery. Things like new leather, aluminium and carbon fibre components, and Brabus 850 kick plates.

We'll find out how much it'll cost when we see it at Geneva. We'll wave the white flags in advance...