BMW 5 Series (2017) is 565 mm (22.24 inch) longer, 67 mm (2.64 inch) wider, 206 mm (8.11 inch) higher and has 407 liters (14.37 ft3) bigger cargo space than Porsche Cayman (2020).
Porsche Cayman (2020) is 310 kg (683 lbs) lighter than BMW 5 Series (2017).