Even though the standard 2012 Mercedes-Benz M-Class is still undergoing development, the company's AMG division has began testing the high-performance version of the series.
Expected to arrive shortly after the standard M-Class model, which itself, will go on sale in late 2011, the ML 63 AMG will feature the brand's newly developed 5.5-liter twin-turbocharged V8 in place of the outgoing car's naturally aspirated 6.2-liter unit.
