Lately have been driving more in ‘his’ position, surely most do that already but I typically enjoy relaxed cruising these days - as opposed to when I was half my age. Driven on a 30 mile loop of highway and local roads at speeds of 30 to 60 MPH. Just for grins recently assessed the mileage difference in my ‘71 442 (TH400/ 455/ 3.23 rear).

When cruising in ‘her’ gate, 10 gallon refueling will net 130 to 140 miles. The last few 10 gallon refills after driving in ‘his’ gate, with very conservative shifts (23-2500 RPMs) gets me about 9 mpg.

Well worth it - but somewhat surprised. Perhaps that’s the typical city /highway difference.

Rochester four barrels are sure thirsty when revved, even moderately!

 

Yours is performing well above average across the board.

Factory ratings, miles per full tank.

Extra Urban up to 62 mph = 205-250 miles
Highway up to 87 mph = 180-215 miles
City = 120-140 miles
City highway combined = 177 miles

That's for a hardtop 1971 442, 270 hp TH400 with 3.23 rear.

Are your tires factory height ? Are you filling up to same location in fill tube ? Is she always level on fill-ups ? Same pump ?

Apples and oranges but I have driven a similar 30 mile loop many a time with the small black 69. In my case it's about 10 miles highway 5 miles city each way. Factory rating says 11 combined avg for my 69. In moderate traffic I match that but I'm obviously 2/3rds highway, 2.56 vs 2.78 rear gear, but 1/2 inch shorter in tire height than factory. So my mileage reading is slightly off as well. In your case factory avg for city/highway is 8.8 mpg. But if you think your driving pattern mimics city/highway your averaging 11.25 mpg.

 

That’s great feedback 69, appreciate the input. I’m measuring mileage with 10 gallons refills, 93 octane at the same station each time. My tires are not original, 245/60 Cooper cobras all around on 15” super stock IIIs.

No concerns with the mileage figures, just forgot the difference shift point RPM’s can make. Never checked or even cared about MPG‘s from 79 to 85 when I had my four speed big block 72 - and shifted at 4-4500 RPMs as often as possible.

 

👍nice and my pleasure.

Tire height from back then can be quite difficult to confirm.

And your baby is no exception.

While a modern 245 60 15 Cobra has been 26.5 inches in diameter for decades. Your original tire comes up with several different measures at diameter.

G70-14
26.2 inches according Automobile Catalog.
26.8 inches according to Coker Tire.
27.3 inches according to The Tire and Rim Association, Inc....

My 69 same deal, factory 7.75 x 14, comes up either 26.4 , 27.0 , or 26.7 Meanwhile my 235 60 15s are always 26.1 ...

 

MPG is absolutely multifactorial. But shifting is so much more fun.😎