Mercedes-Benz is set to reveal its new A-Class in 2012. Despite not being officially launched yet, the German automaker is already planning an AMG variant.Our spies spotted a heavily camouflaged prototype undergoing testing. The new model sports high performance brakes, AMG wheels and a sporty dual exhaust system. The A-Class AMG has been benchmarked against Volkswagen’s Golf 'R'.Power is set to be provided by a turbocharged two-litre petrol engine capable of around 250kW. The engine is expected to be paired with a dual-clutch transmission and all-wheel drive.Check out our gallery!