Two Sedans with more similarities, such as the body structure, starting price, ground shadow size, height, and maximum occupancy, than differences, like the horsepower and fuel economy. And finally, the 2015 Hyundai Sonata has bigger and thirstier engine; the 2016 Mazda 6 gets 2.3 more mpg. Among similarities are the body structure, starting price, ground shadow size, height, and maximum occupancy.