Two Sedans with more similarities, such as the body structure, market segment, starting price, ground shadow size, height, and maximum occupancy, than differences, like the horsepower and fuel economy. And finally, the 2016 Cadillac XTS has a more powerful engine than the 2015 Acura RLX, and it gets 5 fewer miles on a gallon of fuel. Among similarities are the body structure, market segment, starting price, ground shadow size, height, and maximum occupancy.