BMW 3 Series Gran Turismo (2020) is 126 mm (4.96 inch) longer, 125 mm (4.92 inch) higher and has 75 liters (2.65 ft3) bigger cargo space than BMW 4 Series (2015).
BMW 4 Series (2015) is 42 mm (1.65 inch) wider and 150 kg (331 lbs) lighter than BMW 3 Series Gran Turismo (2020).