BMW 8 Series (G14) (2019) is 451 mm (17.76 inch) longer, 101 mm (3.98 inch) wider, 44 mm (1.73 inch) higher and has 200 liters (7.06 ft3) bigger cargo space than Porsche 718 Cayman (2017).
Porsche 718 Cayman (2017) is 482 kg (1,063 lbs) lighter than BMW 8 Series (G14) (2019).