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 Lexus GS 350 has bigger and thirstier engine; the 2015 Acura RLX gets 1.5 more mpg. Among similarities are the body structure, market segment, starting price, ground shadow size, height, and maximum occupancy.