BMW 8 Series (G16) (2020) is 689 mm (27.13 inch) longer and 146 mm (5.75 inch) wider than Mercedes B-Class (2018).
Mercedes B-Class (2018) is 150 mm (5.91 inch) higher, 514 kg (1,133 lbs) lighter and has 46 liters (1.62 ft3) bigger cargo space than BMW 8 Series (G16) (2020).