Kia Optima (2015) is 4 mm (0.16 inch) wider and 55 kg (121 lbs) lighter than Opel Insignia Sports Tourer (2017).
Opel Insignia Sports Tourer (2017) is 58 mm (2.28 inch) longer, 48 mm (1.89 inch) higher and has 50 liters (1.77 ft3) bigger cargo space than Kia Optima (2015).
