Here we have the latest spy photos of the Mercedes G AMG Family testing in northern Sweden from the sound of the exhaust one is the G55 AMG and the other is a G65 AMG.

The G55 AMG is currently the most uneconomical Mercedes in the fleet with an oil baron busting 9mpg with its turbo charged 5.4 litre V8, we expect the replacement to be powered by the same unit.

We expect the G65 AMG to run a limited number of around 300 units and will sport a 6.0 litre V12 rumoured to be detuned for around 630hp with a whopping 1000Nm of torque and probably fuel economy to match.

After closer inspection we see that the G55 will have a single integrated intercooler in the bumper to aid lower intake temperatures.

And the G65 will have 2 side mounted integrated intercoolers to aid the additional heat from the bigger power unit.

Detailing changes will include face lifted bumpers with daytime running lights and larger brake callipers.

Interior will be the largest change with a new instrument cluster and the latest sat navigation system.

We expect to see the debut of the G55 – G65 at the 2012 Detroit Motorshow and perhaps might slip to Geneva in March.