Two Sedans with more similarities, such as the body structure, market segment, ground shadow size, height, and maximum occupancy, than differences, like the powertrain, fuel economy, market segment, starting price, and horsepower. First of all, a bigger engine usually means less mpg. But the 2017 Acura RLX Hybrid has a more powerful engine and it gets 10 more mpg than the 2017 Kia K900. Also, there is a notable difference in the starting price of the 2017 K900, which is $10,050 less than the base MSRP of the 2017 RLX Hybrid. Among similarities are the body structure, market segment, ground shadow size, height, and maximum occupancy.