Fuel Economy Comparison Calculator
Compare annual fuel cost and price-difference payback between two vehicles.
Enter MPG and price for two vehicles plus your annual mileage and gas price. Get annual fuel cost difference and payback period.
Vehicle A
Vehicle B
Your driving
How the comparison works
Annual gallons used = miles driven per year divided by MPG. Annual fuel cost = annual gallons times price per gallon. The calculator compares both vehicles and shows the difference. If you also enter purchase prices, it calculates the payback period: how many years of fuel savings it would take to recoup the extra purchase cost.
What "MPG" to use
- EPA combined: the average of city and highway MPG. Best default for mixed driving.
- EPA highway: if you mostly drive highway miles
- EPA city: if you mostly drive in stop-and-go traffic
- Real-world MPG: EPA estimates are often optimistic. Sites like Fuelly track real owner-reported MPG; check those for an honest number.
Beyond fuel cost
Fuel is one factor in total cost of ownership. Other factors that may favor one vehicle over the other:
- Insurance cost (varies by vehicle)
- Maintenance and repair history (hybrids and EVs may cost more or less than ICE depending on model)
- Depreciation (more efficient vehicles often hold value better)
- Registration and tax (varies by state)
- For EVs: charging cost (often half to a third of gas per mile)
Fuel price uncertainty
Gas prices fluctuate. The payback calculation assumes the gas price you entered stays constant. For a more conservative estimate, use the highest gas price you have seen in recent years. For a more optimistic one, use today's price. Reality will be somewhere in between.