The RX 350 and RX 450h are categorized as full-sized luxury SUVs, and they carry the amenities and horsepower to back it up. The 450h features a hybrid drivetrain that can run on batteries alone for short distances to save fuel. The 350 does all right on its own, achieving 18 mpg city and 25 mpg highway, but the 450h really shines with 28 mpg city and 32 mpg highway.