Mercedes GLC-Class (2017) is 278 mm (10.94 inch) longer, 90 mm (3.54 inch) wider, 366 mm (14.41 inch) higher and has 188 liters (6.64 ft3) bigger cargo space than Porsche Cayman (2016).
Porsche Cayman (2016) is 695 kg (1,532 lbs) lighter than Mercedes GLC-Class (2017).