my reply wasn't meant to be obnoxious but based on my experience with low gears. i had a 383 4spd car i ran around on for a short while with 4.30's or 4.56, don't remember exactly but pretty sure it was only getting around 6 in town. my stock 440 r/t with 3.23's and a fairly good tune probably gets about 10 in town. these old dinosaurs are just inefficiently thirsty. one thing for sure is if mpg and a clean burn are important it's fairly difficult beat a stock avs carb.

Try writing down your odometer reading when you fill it up.

Drive until almost empty.

Observe odometer reading when you go to fuel up, write it down.

Write down how many gallons you put in.

Subtract last odometer reading from the first one.

Divide miles to gallons used. This will give you mpg.

Report back with your results.

There are online calculators to assist with the subtracting and dividing if needed, but the pen, paper, and effort required to write 3 numbers down will have to come from you.

I have a 440 based 511 stroker with a solid roller cam in a 74 Challenger. It has 3.23 gears, 245-60-R15 Goodrich T/A tires, automatiac 727 with TF2 shift kit, and Holley Sniper fuel injection. The Sniper controls timing. I check milage at each fill up. I get between 9 and 11 mpg depending on driving conditions.
The basicaly stock 440 with the Purple Stripe cam (..474 lift) and AVS carb that preceeded this engine got 10 to 12 mpg.

Between 6 and 10 mpg.

high single to low teens range.

I get about 10-12 if I keep my foot out of it for a full tank

One really good romp on the loud pedal for a bit , OR long trips at 70 plus,,,,and Im in single digits easily.

But being brutally honest. I dont care,,,,. I didnt buy if for its fuel economy.

Well said!!!

remember, "smiles per mile" is the target.

Agree! Always wondered about these MPG threads. I've had my car well over 30 yrs with a couple combos in it. Currently a 470" low deck w/solid roller cam 4 spd 3:73 gears....never once have I thought about MPG...Doesn't matter, I put maybe 1000 mi /yr on it. Plenty of smiles though. I've had people ask about mileage in my pickup as well....I always tell them it weighs 6000 lbs and has the aerodynamics of a brick....I bought it for a purpose,not fuel economy!