Mercedes C-Class (2016) is 308 mm (12.13 inch) longer, 10 mm (0.39 inch) wider, 149 mm (5.87 inch) higher and has 318 liters (11.23 ft3) bigger cargo space than Porsche Cayman (2017).
Porsche Cayman (2017) is 40 kg (88 lbs) lighter than Mercedes C-Class (2016).