[bobcowan]

427W in a Dart block, TKO with .64 5th, and 3.55 rear gears - 515hp on a chassis dyno last year. I get about 20 on a mountain drive, with speed averaging 60-70mph. On city streets it's less than that, because I can't keep my foot out of it. But I think it's somewhere around 12'ish.

If you're only getting 6-8mpg, either you drive like a mad man, or you need a little tuning adjustment.