McLaren 650S Coupe (2015) is 220 mm (8.66 inch) longer and 313 mm (12.32 inch) wider than Mercedes A-Class (2017).
Mercedes A-Class (2017) is 230 mm (9.06 inch) higher, 73 kg (161 lbs) lighter and has 197 liters (6.96 ft3) bigger cargo space than McLaren 650S Coupe (2015).