BMW 5 Series (2015) is 528 mm (20.79 inch) longer, 59 mm (2.32 inch) wider, 168 mm (6.61 inch) higher and has 410 liters (14.48 ft3) bigger cargo space than Porsche 718 Cayman (2014).
Porsche 718 Cayman (2014) is 399 kg (880 lbs) lighter than BMW 5 Series (2015).