Here is the powertrain: Moser 9" with 4.10's and locker diff, 700R4 with a shift kit, bolt on L98 (est 300hp). 18" wheels (25 1/2" tire). Car is 200 lbs lighter than stock.

The speedo is off and the odometer counts wrong. I used my GPS on my trip today. I topped off the tank before and after. I drove 80 miles (70miles highway 10 miles city). Set the cruise @60mph RPM @2250.

I used 3.75 gallons = 21.33 mpg!?

Maybe that's normal? I was estimating 16

 

There's a margin of error in topping off, doesn't always shut off at the same point. Need to measure after using a larger amount of gas to minimize the margin of error. At least a full tank.

 

I was thinking that. I think I had gas up the filler neck on the first top off. I may never know because this car never gets filled past half tank until yesterday haha.