Kia Optima Sportswagon (2015) is 21 mm (0.83 inch) wider, 20 mm (0.79 inch) higher and has 73 liters (2.58 ft3) bigger cargo space than Mazda 6 (2015).
Mazda 6 (2015) is 9 mm (0.35 inch) longer and 108 kg (238 lbs) lighter than Kia Optima Sportswagon (2015).
