BMW 3 Series Touring (2015) is 255 mm (10.04 inch) longer, 11 mm (0.43 inch) wider, 136 mm (5.35 inch) higher and has 333 liters (11.76 ft3) bigger cargo space than Porsche Cayman (2016).
Porsche Cayman (2016) is 140 kg (309 lbs) lighter than BMW 3 Series Touring (2015).