BMW 8 Series (G15) (2018) is 385 mm (15.16 inch) longer, 99 mm (3.90 inch) wider, 71 mm (2.80 inch) higher and has 236 liters (8.33 ft3) bigger cargo space than Porsche 718 Cayman (2020).
Porsche 718 Cayman (2020) is 473 kg (1,043 lbs) lighter than BMW 8 Series (G15) (2018).