Two Coupes with more similarities, such as the body structure, market segment, starting price, ground shadow size, height, and maximum occupancy, than differences, like the fuel economy, market segment, and horsepower. First of all, the 2016 Maserati GranTurismo has bigger and thirstier engine; the 2016 BMW i8 gets 12 more mpg. Among similarities are the body structure, market segment, starting price, ground shadow size, height, and maximum occupancy.