someone can fetch the curb weight of that terrain in fwd garb. but if its about 3800 pounds and has the 4 cyl 6 pot, it will touch 30 on the highway or maybe even exceed it as the ecotec historically can achieve close to 40mpg. i have no reason to not believe that the equinox at 29/30 mpg the terrain will maybe be 1 mpg less hwy with its more upright stance. a lot of times mpg is more a function of curb weight and engine rpm as anything. a GC is going to at least be 500 pounds heavier and has much thirstier mill under the hood. now, with 6 speeds the GC mileage will be vastly improved, but really its not going to come close to touching the car based terrain. the reason the trailblazer got so bad mpg, the I-6 from GM was a fuel sucker, and the trailblazer was heavy. most real world mpg figures i have heard or read on trailblazers were in the 14-18 mpg range. One close friend who had an extended trailblazer said 15 was the norm with 4x4.
my aztek will sometimes see 25 mpg and that is with the lousy 3.4/4 sp. the terrain is not as blocky and has the smaller motor and 6 speeds as i am guessing the weight is similar. again, i see no problem with the terrain coming close to the 30 mpg for a fwd version.
often times too GM products will well exceed their epa numbers. not sure why, but they do. people with v6 malbus pulling 35 mpg highway. or impalas for that matter. i have heard of people pulling over 40 mpg in cobalts.
GM's I-6 was a great idea but for some reason it was a major gas hog. not sure why.