Mazda 3 (Sedan) (2019) is 268 mm (10.55 inch) longer and 10 mm (0.39 inch) wider than Mercedes B-Class (2017).
Mercedes B-Class (2017) is 112 mm (4.41 inch) higher, 11 kg (24 lbs) lighter and has 67 liters (2.37 ft3) bigger cargo space than Mazda 3 (Sedan) (2019).