BMW 8 Series (G14) (2020) is 456 mm (17.95 inch) longer, 102 mm (4.02 inch) wider, 46 mm (1.81 inch) higher and has 188 liters (6.64 ft3) bigger cargo space than Porsche Cayman (2020).
Porsche Cayman (2020) is 528 kg (1,164 lbs) lighter than BMW 8 Series (G14) (2020).