Update on mine. Drove it 366 miles round trip yesterday unloaded and it averaged 22mpg on the highway.

We towed a similar distance with an open car trailer and a car loaded both ways and averaged 17mpg.

We were in the Flint Hills towing back and it never even down shifted out of 6th on the steepest hill!

'63 Dodge 330
11.19 @ 121 mph
Pump gas, n/a, through the mufflers on street tires with 3.54's. 3,600 lbs.
10.01 @ 133mph with a 250 shot of nitrous an a splash of race gas. 1.36 60 ft. 3,700 lbs.