* Engine Size and Transmission: While you specified a V6, the exact displacement (e.g., 4.3L) matters. Also, the transmission (automatic or manual) affects fuel economy.
* Driving Habits: Aggressive acceleration and high speeds significantly reduce fuel economy.
* Vehicle Condition: Proper tire inflation, engine tune-up, and overall vehicle maintenance impact fuel efficiency.
* Terrain: Hilly or mountainous terrain reduces fuel economy compared to flatland driving.
* Fuel Quality: The type of gasoline used can slightly affect mileage.
* Tank Size: The size of the fuel tank varies depending on the specific model and configuration of the truck.
To get an estimate, you should:
1. Check your owner's manual: This will give you the EPA estimated fuel economy (in MPG - miles per gallon) for highway driving. Remember this is an *estimate* under ideal conditions.
2. Look at online forums: Search for forums dedicated to 1999 Chevy Silverados. Owners often discuss their real-world fuel economy experiences.
3. Fill up your tank and track your mileage: The most accurate way to determine your truck's highway fuel economy is to fill the tank completely, drive only on the highway for a significant distance (e.g., 200-300 miles), and then refuel, noting the amount of fuel used. This will provide your personal MPG, which you can then multiply by your tank's capacity (in gallons) to estimate your range.
Without knowing the specifics of your truck (engine size, transmission, tank size) and your driving habits, it's impossible to give a precise number. However, expect somewhere in the range of 250-350 highway miles on a full tank as a *rough* estimate, but that could be significantly higher or lower depending on the factors listed above.
