MPG Comparison Calculator
Compare annual fuel cost for two vehicles from MPG, miles driven, and gas price.
Returns yearly savings, 5-year savings, and break-even on efficient upgrades.
MPG comparison between two vehicles calculates the real annual fuel cost difference, helping buyers and drivers make data-driven decisions about fuel economy.
The core formulas:
Annual Fuel Cost = (Annual Miles / MPG) × Price per Gallon
Annual Savings = Annual Cost (Vehicle A) − Annual Cost (Vehicle B)
Payback Period = Price Difference / Annual Savings
5-Year Fuel Cost = Annual Fuel Cost × 5
What each variable means:
- Annual Miles — how far you drive per year (US average: 12,000–15,000 miles)
- MPG — miles per gallon for each vehicle under your typical driving conditions
- Price per Gallon — current local fuel price; use a 5-year average for long-term comparisons
- Payback Period — how long the fuel savings take to offset a higher purchase price
Worked example: Vehicle A: 28 MPG, priced at $28,000. Vehicle B: 42 MPG, priced at $34,000. Annual miles: 14,000. Gas price: $3.50/gallon.
Annual cost A = (14,000 / 28) × $3.50 = 500 × $3.50 = $1,750/year Annual cost B = (14,000 / 42) × $3.50 = 333.3 × $3.50 = $1,167/year Annual savings = $1,750 − $1,167 = $583/year Price difference = $34,000 − $28,000 = $6,000 Payback period = $6,000 / $583 = 10.3 years
Key insight: The payback period exceeds the typical 7–8 year ownership period in this example. However, at $4.50/gas or 20,000 miles/year, payback drops to under 5 years — always run the numbers for your specific situation.
EPA ratings are tested under ideal conditions; real-world MPG is typically 15–25% lower.