BMW 7 Series (2016) is 720 mm (28.35 inch) longer, 102 mm (4.02 inch) wider, 185 mm (7.28 inch) higher and has 353 liters (12.47 ft3) bigger cargo space than Porsche Cayman (2015).
Porsche Cayman (2015) is 395 kg (871 lbs) lighter than BMW 7 Series (2016).