BMW 8 Series (G16) (2020) is 704 mm (27.72 inch) longer, 132 mm (5.20 inch) wider, 114 mm (4.49 inch) higher and has 278 liters (9.82 ft3) bigger cargo space than Porsche Cayman (2019).
Porsche Cayman (2019) is 504 kg (1,111 lbs) lighter than BMW 8 Series (G16) (2020).