Mercedes M-Class (2015) is 306 mm (12.05 inch) longer, 139 mm (5.47 inch) wider, 349 mm (13.74 inch) higher and has 390 liters (13.77 ft3) bigger cargo space than Opel Ampera (2014).
Opel Ampera (2014) is 493 kg (1,087 lbs) lighter than Mercedes M-Class (2015).