Buick Excelle GT (2015) is 209 mm (8.23 inch) longer, 170 mm (6.69 inch) higher, 180 kg (397 lbs) lighter and has 243 liters (8.58 ft3) bigger cargo space than Porsche Cayman (2017).
Porsche Cayman (2017) is 2 mm (0.08 inch) wider than Buick Excelle GT (2015).