Development on the new Mercedes-Benz C-class C63 AMG is entering its final stages ahead of its expected launch at the LA motor show in November.

This estate version of the C63 AMG was spotted winter testing, and it gives us the clearest look yet at the visual changes that will mark out AMG variants of the C-class from the standard car.

While still wearing a heavy disguise, a larger lower grille and side air intakes can be seen at the front of this test mule, with a more aggressively styled rear bumper and quadruple exhaust exits at the back. Bespoke AMG wheel designs are also visible.

As with the C63 AMG saloon, coupé and convertible variants, power for the performance estate will come from a new twin-turbocharged 4.0-litre V8 engine with close to 500bhp. The saloon will launch first, likely at the start of next year, with other variants rolled out over the next two years.

The new V8 engine replaces the current C63's naturally aspirated 6.2-litre petrol V8 unit, which puts out 451bhp in standard form. The direct-injection V8 engine, which should have around 480bhp available, plays a big part in AMG's future strategy, and shares its modular architecture with the turbocharged 2.0-litre four-cylinder petrol engine found in the A45 AMG.

The use of forced induction in the new C63 AMG is also expected to boost torque beyond the 61.24kgm of today's car. Putting an end to the recent trend of offering AMG models in both rear and all-wheel-drive forms, the new C63 AMG will be offered in rear-wheel-drive guise only.