We’re used to featuring tuned Mercedes G-Wagens on TopGear.com. But this is the most powerful we’ve come across yet.

German tuner Posaidon has got its hands on ia G63 AMG and turned it into the G63 RS 850. And yep, that number refers to its power output.

The standard SUV gets a 5.5-litre twin-turbo V8, which typically produces 571bhp. Posaidon has come along and lifted that number to a much more fun 850bhp with a hefty 995lb ft of torque. That’s an easy 0-62mph time of just 3.6 seconds and a breezy 177mph top speed. Bafflingly quick for a 2.5-tonne slab of metal.

The upgrades come as part of a remapped ECU and upgraded transmission internals, plus new adaptive dampers, 22-inch alloys and gold brake calipers from the S63 AMG. Carbonfibre accents, colour contrast stitching and quilted leather are all options as well, on top of all the bling the G63 comes with already. Curiously, the rear-mounted spare wheel has gone AWOL, perhaps for the sake of aero.

There’s no word on how much the programme will cost, but seeing as the base model already costs over £90k, you can potentially double that for this extra-strong version. Worth it? Possibly not. But if you’re gonna go big, you might as well go really big…