Fuel Cost Comparison
Compare fuel costs for different vehicles or trips. Calculate based on fuel efficiency, distance & gas prices. Choose the most economical option.
Vehicle A (Gas)
Vehicle B
About Fuel Cost Comparison
Free Online Tool
Fuel Cost Comparison
Enter fuel efficiency, gas price, and annual mileage for two vehicles or driving scenarios — get an exact annual and lifetime fuel cost comparison and see precisely how much each MPG improvement saves you per year.
How to Use This Tool (30 Seconds)
- 1Enter Fuel Efficiency in MPG: Input the miles per gallon for Vehicle A and Vehicle B. Use the EPA combined city-highway rating from fueleconomy.gov for a standardized comparison, or your actual calculated MPG from fill-up records for real-world accuracy. Real-world MPG typically runs 10–15% below EPA ratings.
- 2Enter Gas Price Per Gallon: Input the current price per gallon of gas. Both vehicles can use different gas prices if one runs on regular and the other on premium — premium adds $0.20–$0.40 per gallon and should be entered separately for the vehicle that requires it.
- 3Enter Annual Miles Driven: Input the total miles you drive per year for each scenario. The US average is approximately 14,500 miles per year. If comparing two vehicles you would drive differently — a commuter car vs a road trip vehicle — enter the actual expected mileage for each.
- 4Read the Fuel Cost Comparison: The tool calculates annual gallons consumed, annual fuel cost, monthly fuel cost, and cost per mile for both scenarios. The summary shows annual saving, 5-year saving, and the dollar value of each single MPG improvement at your mileage and gas price.
The Fuel Cost Formula and MPG Value Calculation
The tool uses the EPA's standard fuel cost formula — the same calculation published on every new car's window sticker and at fueleconomy.gov:
// Annual gallons consumed
annualGallons = annualMiles ÷ MPG
// Annual fuel cost
annualFuelCost = annualGallons × gasPricePerGallon
// Cost per mile
costPerMile = gasPricePerGallon ÷ MPG
// Annual saving between two scenarios
annualSaving = annualFuelCostA − annualFuelCostB
// Dollar value of each single MPG improvement
valuePer1MPG = annualMiles × gasPrice × (1÷MPG − 1÷(MPG+1))
// Example: 25 MPG vs 35 MPG, $3.50/gal, 15,000 miles/yr
annualCost_25mpg = (15,000÷25) × $3.50 = $2,100/yr
annualCost_35mpg = (15,000÷35) × $3.50 = $1,500/yr
annualSaving = $600/yr | 5-year saving = $3,000
The value-per-1-MPG formula reveals a critical non-linearity: improving from 10 to 11 MPG saves far more fuel than improving from 40 to 41 MPG, even though both are 1 MPG gains. At 15,000 miles and $3.50/gallon, going from 10 to 11 MPG saves $477/year. Going from 40 to 41 MPG saves only $32/year. Fuel savings are hyperbolic with MPG — each additional MPG is worth progressively less as efficiency increases, making low-MPG vehicle upgrades disproportionately impactful on fuel spend.
Annual Fuel Cost Reference — By MPG and Gas Price
| MPG | @ $3.00/gal | @ $3.50/gal | @ $4.00/gal | Vehicle Type |
|---|---|---|---|---|
| 15 MPG | $3,000 | $3,500 | $4,000 | Large truck, old SUV |
| 20 MPG | $2,250 | $2,625 | $3,000 | Midsize SUV, V8 sedan |
| 28 MPG | $1,607 | $1,875 | $2,143 | Average new car (2024 EPA) |
| 35 MPG | $1,286 | $1,500 | $1,714 | Compact sedan, hybrid |
| 50 MPG | $900 | $1,050 | $1,200 | Toyota Prius, mild hybrid |
| 60 MPG | $750 | $875 | $1,000 | Best-in-class hybrid |
Annual cost calculated at 15,000 miles per year — the US average based on FHWA data. The 2024 EPA fleet average for new passenger cars is 28.2 MPG. All figures are for regular unleaded gasoline.
⚡ Pro Tip
The MPG improvement that saves the most money is never at the top of the efficiency range — it is always at the bottom. If you currently drive a 15 MPG vehicle, upgrading to a 20 MPG vehicle saves $875/year at $3.50/gallon and 15,000 miles. Upgrading from 35 to 40 MPG saves only $150/year from the same mileage and gas price. Before comparing two high-efficiency vehicles, check whether the lower-MPG vehicle in the comparison is a 15–25 MPG model — because that single upgrade decision likely saves more fuel money annually than any other vehicle comparison you could run through this tool.
Frequently Asked Questions
Q: How do I calculate my real-world MPG accurately?
Fill your tank completely, reset your trip odometer to zero, drive normally until near empty, fill again completely. Divide the miles on your odometer by the gallons used in the second fill-up. Do this across 3 fill-ups and average the results for a representative real-world figure. Single-fill calculations are skewed by driving conditions — highway-heavy weeks inflate MPG, city-heavy weeks deflate it.
Q: Should I use the EPA rating or my actual MPG in the comparison?
Use actual MPG for cost accuracy, EPA rating for comparing two vehicles you do not yet own. EPA combined ratings provide a standardized baseline for vehicle comparisons. Real-world MPG runs 10–15% below EPA estimates on average due to air conditioning use, aggressive acceleration, cold weather, and varying road conditions. Apply a 10% reduction to EPA ratings for a more realistic fuel cost projection.
Q: How much does gas price affect the annual fuel cost?
Proportionally and directly — a 10% increase in gas price increases annual fuel cost by exactly 10% at constant mileage and MPG. At 25 MPG and 15,000 miles, every $0.10/gallon increase in gas price costs an additional $60/year. At 15 MPG, the same $0.10 increase costs $100/year — confirming that low-MPG vehicles are most exposed to gas price volatility and benefit most from efficiency improvements.
Q: Does the tool account for premium vs regular fuel price differences?
The tool uses a single gas price per vehicle. If Vehicle A requires premium fuel and Vehicle B uses regular, enter the appropriate price for each — premium typically costs $0.20–$0.40 more per gallon than regular. Vehicles that require premium but are compared using regular fuel prices will show artificially lower fuel costs. Check your vehicle's owner manual for the required octane rating.
Q: What annual mileage should I use if I drive variably each year?
Use a 3-year average for the most representative figure. Check your odometer against insurance renewal records or service history which typically note current mileage. If you are comparing a future vehicle purchase, use your current annual mileage as the baseline — most driving patterns are stable year-to-year unless a commute or lifestyle change is expected.
Q: How much does proper tire inflation affect fuel efficiency?
The US DOE estimates under-inflated tires reduce fuel efficiency by 0.2% per PSI below the recommended pressure. A vehicle with all four tires 5 PSI under-inflated loses approximately 1% of MPG — roughly 0.3 MPG on a 30 MPG vehicle. At 15,000 miles and $3.50/gallon, that 0.3 MPG difference costs $52/year. Maintaining correct tire pressure is one of the highest-return maintenance actions for fuel economy.
Q: Is it worth buying a more fuel-efficient car based on gas savings alone?
Calculate the payback period: divide the price premium of the more efficient vehicle by the annual fuel saving. A hybrid costing $3,000 more than a comparable non-hybrid but saving $600/year in fuel has a 5-year payback period. If you plan to keep the vehicle longer than the payback period, the fuel savings make the premium financially justified on cost alone — before accounting for lower maintenance and higher resale value.