I got 15 on my last trip to and from Montana at 70, cruise and AC on. 130K on the 289 2bl, C4 and 2:80 butts with 225x15x60 TAs. I dont think thats bad, maybe not go with todays standards but not bad.

Last time checked 72 mach with 351C, toploader & Gear Vender OD, 3.50 gears was 14mpg highway.
67 with 351C, AOD, 370 gears gets a little better for some reason.

RV6 wrote:

My mileage is all over the place; 14-22 mpg. I fill by mileage, so when I hit 300 I'm looking to fill. Usually takes around 15 gallons. So I guess I get around 20 average. The sender and gauge are original and are very accurate.

Is that highway or around town? I recorded my mileage at the last time I filled up, drove it about 179 miles and then filled up with 12.2 gallons. That's how I calculated my mpg.

Toploader wrote:

RV6 wrote:

My mileage is all over the place; 14-22 mpg. I fill by mileage, so when I hit 300 I'm looking to fill. Usually takes around 15 gallons. So I guess I get around 20 average. The sender and gauge are original and are very accurate.

Is that highway or around town? I recorded my mileage at the last time I filled up, drove it about 179 miles and then filled up with 12.2 gallons. That's how I calculated my mpg.

I write down the mileage and amount filled at each gas stop. Looking through the log I see a low of 14.79 to a high of 23.4. I keep a running average and it works out to 19.8 for all types of driving. Hence I fill at 300 miles for my 16 gallon tank.

My engine is a 351W stroked to 416 with performer heads and intake with a 750 pot on top. I replaced the three speed with a C4 and recently replaced that with a T5. Most of the mpgs have been figured with the C4. The rear end is a 3.00 so it looks like the mpgs have stayed the same so far. I'm still fooling with the carb but it's hard to keep my foot out of it and adjust it. I keep track of my mpgs the same as Gary. The worst was 7 mpgs the best 18, most of the time it's 15. The mpgs would probably improve if I were to put in a 3.25 or 3.55 rear. But that would bust TKO's 10.00 first gear rule without changing out my 1st gear.

I really don't much care about the mileage factor, the main factor is, a cool car not everyone has, or can build and maintain. and since I put the Auburn unit in the car, tires are the bigger consideration.the smile on my face when I drive it, priceless. gas mileage? "we don't no stinkin gas mileage"

Toploader wrote:

RV6 wrote:

I write down the mileage and amount filled at each gas stop. Looking through the log I see a low of 14.79 to a high of 23.4. I keep a running average and it works out to 19.8 for all types of driving. Hence I fill at 300 miles for my 16 gallon tank.

What engine and rear gear do you have? Do you have a 5 speed?

3.55 rear, T5
 

I can't remember!! Seems like it was pretty good though. As cheap as gas is.......its'a non-issue. I guess.
Seemz like it was 17 MPG or maybe 14......... highway.?!
Still gives me goosebumps and makes me 'pucker' when I squeeze-it.
6sally6