SEE MORE SPY VIDEOS: www.edmunds.com Meaner and greener — that’s the new objective of AMG. The tuning arm of Mercedes-Benz is rapidly approaching its peak in terms of horsepower, so cleaning up emissions while maintaining performance is the key for the future. This 2010 Mercedes-Benz E63 AMG spotted testing on the Nürburgring could be the first of AMG’s new green machines. Mercedes-Benz officials have gone on record saying that all of the company’s future engines will be turbocharged, so …