BMW i8 (2017) is 80 mm (3.15 inch) wider and 182 kg (401 lbs) lighter than Buick Regal Sportback (2018).
Buick Regal Sportback (2018) is 211 mm (8.31 inch) longer, 162 mm (6.38 inch) higher and has 316 liters (11.16 ft3) bigger cargo space than BMW i8 (2017).