[Ace23]

I think you will get a different answer from everyone. I have a 427 with quite a bit of overlap and I can't do better than 10-11mpg with a 3:31 rear gear. The car has a Q-Fuel 750 with mechanical secondaries and has been dyno tuned. What I have not done is part throttle tune it on the open road with a wide band. A local friend has a 445 more aggressive Windsor with a larger carb than mine with 3.46 gears and it was dyno tuned by the same guy mine was......he gets 1mpg or so better than me so go figure.

I talked to a guy yesterday with a 598ci big block making 800hp with a solid roller and a 1050 dominator and he said he runs 3:73 rear gears and can get 15mpg on the interstate after tuning his car with a wideband. This blows my mind if its true.....he would have absolutely no reason not be truthful about the MPG but who the heck knows. I don't see how you wouldn't get 5mpg with something like that

Based off my limited experience depending on rear gear and camshaft selectiong I don't see why you wouldn't be getting at least 15mpg if you are cruising.