BMW 7 Series (2015) is 705 mm (27.76 inch) longer, 116 mm (4.57 inch) wider and has 29 liters (1.02 ft3) bigger cargo space than Mercedes B-Class (2017).
Mercedes B-Class (2017) is 79 mm (3.11 inch) higher and 405 kg (893 lbs) lighter than BMW 7 Series (2015).