I really don't have a need for my truck right now, that's the whole thing of it. And, I can see myself getting run over/rearended on the highway if I tried to go 50 mph, not to mention that I'd have to allow in a fair bit of extra time to get to work.
Honestly around here...even if my truck did decent on mileage I probably still wouldn't do well. I set the cruise at 70 on my mustang, and I can do (at best) 23 mpg on a tank. On flat ground I could very easily be getting 25+, and I know this because I got that bringing the car home from Ohio. I can watch the average mpg go down every time I go up a hill. Oh well.
Maybe I'd be best off just putting it up for sale and looking for something smaller.