There is a recent post on one of the Thunderbird forums, regarding the gas mileage of 55-57 Thunderbirds with 292-312 Y-block engines. Some owners reported 7-10 mpg, others getting 9-12, another getting between 13-14, and another claimed 20 mpg on the highway, in overdrive. Having inherited my 55 T-bird, I drove it just a couple of times before beginning restoration, so I have no idea what kind of gas mileage I should expect. 7-13 mpg is nothing to brag about. Are these numbers typical? They are awfully low for a small v8 in a 3,000-lb. car. Is there an explanation, other than the given examples are parade cars that are seldom driven on the highway? 

55Blacktie. A Thunderbird might be different than the full size car but during my transmission and rear end swap I was advised not to use the Ford-o-matic with the new rear I was installing with 2.74 gears so I did the true 3 speed automatic first. I agree that at highway speeds the new rear is great and is not sluggish at all starting out because it’s using 1st gear. Automatics use a lot more fuel at idle which doesn’t help our mileage.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

The last trip I made coast to coast in my 56 Bird, I got an average of 14 MPG.  This was all kinds of driving - flat plains, high mountains, city and country. 6300 miles total.  312 with a C-4, stock rear


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ