6.5 City/7.5 Hwy. MPG. ?

[Rick Parker]

Engine is spinning pretty good for a Big Block (unnecessary) try dropping to 3.54/3.50/3.31.

[DanEC]

I'm not surprised if you let the car warm up a little in the driveway, back it out of the garage to wash and then back in again, spend some time tuning it in the driveway, run around town on short drives, etc. None of my 427 Corvette, tuned Lightning truck or 67 440 GTX can beat 8 or 9 mpg for all of the above reasons. 7.5 mpg on the highway is a little steep - my Vette with 4.11 gears can probably beat that very slightly on 55 mph highways.

[philminotti]

Vacuum advance on the timing will definitely help if you're not already running it. That's why it was invented.

[jhv48]

What rpm's are you turning at 65 mph?

[scootter]

My 514 does much better. I've got over 15mpg on the freeway. 600Hp with a 850 Demon. My new for Ford Superduty with the 6.2 gets about 13.5 to 14 mpg highway.
Scott

[Turbonut48]

My Daytona , with 418 EFI 5 speed, 3.50 gear gets about 13-14.
Its still breaking in, and I hope it goes up 1 or 2 mpg.

The Nut