The 2018 GMC Terrain is available as a 4-door, 5-seat sport utility. Starting at $24,995, the 2018 GMC Terrain SL FWD is powered by a 1.5L , 4 -cylinder engine mated to an automatic transmission that returns an EPA estimated 26-mpg in the city and 30-mpg on the highway. The top of the line 2018GMCTerrainDenali AWD , priced at $ 39,300 , is powered by a 2.0L , 4 - cylinder engine mated to an automatic transmission that returns an EPA estimated 21-mpg in the city and 26-mpg on the highway.