BMW 3 Series (2014) is 205 mm (8.07 inch) longer, 14 mm (0.55 inch) wider, 60 kg (132 lbs) lighter and has 75 liters (2.65 ft3) bigger cargo space than Mercedes B-Class (2020).
Mercedes B-Class (2020) is 133 mm (5.24 inch) higher than BMW 3 Series (2014).