* Engine size: A 6-cylinder engine would get significantly better mileage than a big-block V8. The smaller the engine, the better the fuel economy.
* Transmission: Automatic transmissions generally used more fuel than manual transmissions.
* Axle ratio: Lower numerical axle ratios (like 2.73:1) were better for highway fuel economy, while higher ratios (like 3.73:1 or 4.10:1) were better for acceleration and towing but consumed more fuel.
* Vehicle condition: Properly tuned engines and well-maintained components contribute to better fuel economy. A poorly maintained truck will get worse mileage.
* Driving style: Aggressive driving habits will significantly reduce fuel economy.
* Load: Carrying a heavy load reduces fuel economy.
Because of this variability, it's impossible to give a single definitive answer. However, you can expect a range:
* Small 6-cylinder engine (e.g., inline-6): Possibly 15-20 mpg on the highway, considerably less in city driving.
* Larger V8 engine: Potentially as low as 10-15 mpg on the highway, and much less in city driving. Some larger V8s could get even worse mileage than that, particularly in city conditions.
Keep in mind these are just estimates. Actual mileage would vary widely. To get a better estimate for a specific truck, you'd need to know the exact engine and transmission configuration and the condition of the vehicle.
