Wow. 95 ZR2 gets really poor mpg

[almightybmw]

So a friend of mine has a 1991 S-10, no frills, just 4WD longbed. He without the topper gets about 19-20 in town and upto 25mpg on the highway.

So I bought a 1995 GMC Sonoma Highrider (ZR2), I knew it would get slightly worse mileage since it sits higher and has a more powerful motor. But 11.96mpg?? That's just terrible if you ask me. Granted, I had just bought it, hit -20* lots of idling (pointless since high cold idle is about 1000rpms) and the fuel pump died, and I've been enjoying it's performance abilities.

But 12mpg?? Something isn't right here. I was hoping for at least the EPA of 15mpg. I didn't think I was driving any more spiritedly than the EPA test would assume.

The truck has 173,000 miles, and its mostly highway driving. Not a leak in the motor or drivetrain, well maintained by a local mechanic. It could use some of the deep stuff (bushings, wheel bearings, etc) but I it doesn't needs them currently. The doors and plastic panels rattle more than the suspension does.

Long winded shortened: 12mpg intown. Should be closer to 15mpg. Bought the truck for off-roading and towing, not mpg, but it doesn't need to get poor mileage either. Suggestions from anyone who's familiar?