2013 Mercedes-Benz G 65 AMG Spied

Reports of an upcoming V12-powered halo version of the Mercedes-Benz G-Wagen have existed since mid last year, and these spy photos of a G-Class prototype appear to lend credence to those rumours.

Spotted in Europe during winter testing, this lightly camouflaged G-Class (seen here alongside its G 55 brother) has a heavily-vented front bumper that is our only substantial clue as to what lies under its angular bonnet.

Some say it's powered by the 6.2 litre naturally-aspirated AMG V8 that's currently being phased out by Mercedes, but we're not so sure.

Behind the prototype's cheek vents appear to be a pair of intercoolers, things that wouldn't be needed on a naturally-aspirated engine like the AMG 6.2.

Instead, the twin-turbocharged 6.0 litre M285 V12 from the SL 65 AMG, CL 65 AMG and S 65 AMG is a more likely contender.

AMG's new twin-turbo 5.5 litre M157 V8 is also another possiblity, but with Mercedes tuner Brabus having already shoehorned a V12 into a G-Class, we're betting Mercedes will opt for the already-proven V12 conversion.

As far as power and torque goes, the biturbo V12 produces as much as 500kW and 1000Nm in SL 65 trim - certainly more than enough to fry the G-Wagen's tyres. Even if it's the smaller 5.5 litre biturbo V8, you can still expect a mammoth 450kW and 800Nm.