The 2018 Lexus RX 350 is available as a 4-door, 5-seat sport utility. Starting at $43,470, the 2018 Lexus RX 350 Base FWD is powered by a 3.5L , 6 -cylinder engine mated to an automatic transmission that returns an EPA estimated 20-mpg in the city and 27-mpg on the highway. The top of the line 2018LexusRX 350F Sport AWD , priced at $ 50,520 , is powered by a 3.5L , 6 - cylinder engine mated to an automatic transmission that returns an EPA estimated 19-mpg in the city and 26-mpg on the highway.