BMW 5 Series Gran Turismo (2018) is 565 mm (22.24 inch) longer, 67 mm (2.64 inch) wider, 175 mm (6.89 inch) higher and has 368 liters (13.00 ft3) bigger cargo space than Porsche Cayman (2014).
Porsche Cayman (2014) is 294 kg (648 lbs) lighter than BMW 5 Series Gran Turismo (2018).