BMW 5 Series Touring (2017) is 618 mm (24.33 inch) longer, 100 mm (3.94 inch) wider, 264 mm (10.39 inch) higher and has 398 liters (14.06 ft3) bigger cargo space than Porsche Cayman (2018).
Porsche Cayman (2018) is 610 kg (1,345 lbs) lighter than BMW 5 Series Touring (2017).