The 2018 Nissan Altima is available as a 4-door, 5-seat sedan. Starting at $23,260, the 2018 Nissan Altima 2.5 S is powered by a 2.5L , 4 -cylinder engine mated to an automatic transmission that returns an EPA estimated 27-mpg in the city and 38-mpg on the highway. The top of the line 2018NissanAltima3.5 SL , priced at $ 33,510 , is powered by a 3.5L , 6 - cylinder engine mated to an automatic transmission that returns an EPA estimated 22-mpg in the city and 32-mpg on the highway.