Use round-trip distance
Map the complete route and include local driving at the destination. A one-way distance entered as the total can understate fuel by nearly half.
Choose realistic fuel economy
Highway ratings can differ from actual loaded, cold-weather, mountainous, or stop-and-go use. Recent trip-computer or fill-up data can be more useful than a best-case rating.
Separate fuel from full vehicle cost
Fuel and tolls are incremental trip costs. Depreciation, tires, maintenance, parking, and insurance matter when comparing driving with another travel mode.
Example: a 720-mile trip
720 miles ÷ 30 mpg = 24 gallons. At $3.60 per gallon, fuel is $86.40; adding $28 tolls gives $114.40 before parking or a contingency buffer.
What to check before you decide
- Actual economy varies with vehicle, speed, load, weather, and route.
- Fuel prices can change by location and date.
Sources behind this guide
These official and primary sources let you verify rules, definitions, and terms that may change.
FuelEconomy.gov — Trip Calculator↗