I once had a '79 Ford F150 Ranger extended cab with a 400 Modified and 4 barrel carb.We had a 73 Chevy 454 Cheyenne. It got 7 MPG pulling a stock trailer with 40 head or just cruising around town. It would roast the tires and leave black tire crunchies behind. It was the only vehicle I have ever seen with the speedometer and the fuel gauge connected to each other.
The rear tires would break lose just by tapping the gas peddle and if you laid into it, you could noticeably see the gas gauge drop.