My 88 4x4 302 did 12 mpg city, highway, mountains, climbing trees, in 4x4, WOT or grampa style... etc. etc. didn't seem to matter what I did. The only time it did better was on a trip to SC where believe it or not it did 20 mpg from Whytheville VA, into Greenville, SC (all down hill of course. Sorry to be the bearer of bad news.