It's been a long period of time since we last saw signs of prototypes of the future 2013 GL 63 AMG on streets, but now the awaiting is over, as new spy shots captured on the Nurburgring circuit surfaced on various car websites over the internet. Like any other model tuned by the Affalterbach-based firm, the beefy SUV is undergoing a series of trials which includes a testing phase on the famous German track, where the engineers can get an accurate read to tweak the car for achieving top-of-the-range driving experience. A prominent grille with the big Mercedes-Benz star in the centre, powerful LED headlamps, an aggresive air intake, wider door sills, large AMG-design alloy wheels and quad exhausts will visually contribute to the overall muscular presence of the car. Outlined to follow right after the new GL-Class bows during the summer of 2012, the first-of-the-series GL 63 AMG is tipped to use the 5500cc twin-turbo V8 powerplant, available in the traditional two output stages: a standard 544 hp choice and boosted 571 hp AMG Performance Package variant. Despite of the outstanding dimensions of the 4x4, the sports-oriented chassis and the additional dynamics solutions installed by AMG should do the right tricks and transform the future GL 63 AMG into one very agile SUV.

Check out further spy shots after the jump!