New in the 2010 model year, the compact Terrain crossover is its only vehicle that offers a four-cylinder engine. That version of the Terrain gets the best gas mileage of any vehicle in the entire GMC lineup.
The 2.4-liter four-cylinder engine that shows up in any version of the Terrain--from SLE to SLT or Denali, if the driver wants--has a raft of gas-saving technology that makes it a miser, especially in its size class. Features like direct injection help the four-cylinder achieve an EPA-estimated 22/32 mpg, a figure better than all the other mid-size crossovers except its corporate cousin, the Chevy Equinox. Adding the Terrain's available all-wheel-drive system doesn't ding fuel economy too badly: it still is rated at 20/29 mpg.
Eco-geeks will be thrilled to learn the Terrain four-cylinder models also have an 'Eco' button which, when engaged, causes accessories like the air conditioning compressor to be a little more conservative, has the torque converter lock up a little earlier, and makes the transmission a little more reluctant to downshift.
Once you choose the Terrain's optional V-6, the numbers take a big fall. The 3.6-liter V-6 makes much more power, but that leads to gas mileage estimated at 17/24 mpg--or even 16/23 mpg when all-wheel drive is fitted. Those figures are more in line with the seven-seat Acadia crossover--not a surprise, since the drivetrains have so much in common.