Two SUVs with more similarities, such as the body structure, market segment, starting price, ground shadow size, height, and maximum occupancy, than differences, like the market segment, horsepower, and fuel economy. First of all, a bigger engine usually means less mpg. But the 2018 Lexus RX 450h has a more powerful engine and it gets 6 more mpg than the 2018 Alfa Romeo Stelvio. Among similarities are the body structure, market segment, starting price, ground shadow size, height, and maximum occupancy.