A new entry in the GMC lineup in 2010, the Terrain is the truck brand's most fuel-efficient vehicle, and it's also one of GM's best crossovers for gas mileage.
The base Terrain's 2.4-liter four-cylinder gets some of the latest gas-saving features, like direct injection, in its quest for efficiency. It pays off, too: it's rated by the EPA at 22/32 mpg, higher than all its mid-size crossover competition save for the nearly identical Chevy Equinox. Even the addition of all-wheel drive doesn't harm mileage too badly: the AWD Terrain still earns a 20/29-mpg rating.
Perhaps even more of interest in four-cylinder models is the new '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 3.0-liter V-6 makes much more power, but that leads to gas mileage of 17/24 mpg--or even 16/23 mpg when all-wheel drive is fitted.