BMW 8 Series (G15) (2020) is 450 mm (17.72 inch) longer and 116 mm (4.57 inch) wider than Mercedes B-Class (2014).
Mercedes B-Class (2014) is 216 mm (8.50 inch) higher, 429 kg (946 lbs) lighter and has 66 liters (2.33 ft3) bigger cargo space than BMW 8 Series (G15) (2020).