Fuel Savings by MPG Calculator
Example: Miles driven per year: 12000 mi · Current MPG: 22 mpg · New MPG: 34 mpg · Gas price: 3.5 $/gal
| Annual dollar savings | $674 |
| Gallons saved per year | 192.51 |
| Current annual fuel cost | $1,909 |
| New annual fuel cost | $1,235 |
Worked example
Driving 12,000 miles a year at 22 MPG uses about 545 gallons, or $1,909 at $3.50 a gallon. A 34-MPG car uses about 353 gallons, or $1,235. You save roughly 192 gallons and about $674 a year. Notice the jump from 22 to 34 MPG saves more than the same 12-MPG jump would higher up the scale, because at low MPG each gallon covers fewer miles to begin with.
Frequently asked questions
Why is MPG a misleading way to compare efficiency?
Because fuel use is not linear in MPG. Going from 15 to 20 MPG saves far more fuel than going from 40 to 45 MPG, even though both are 5-MPG jumps. This is the MPG illusion; running the actual gallons, as this tool does, avoids it.
Where do I find accurate MPG figures?
The federal fuel-economy site lists official combined, city, and highway MPG for nearly every model. Your real-world MPG depends on driving style, so if you track it at the pump, use your measured number for the current car.
Does this account for changing gas prices?
It uses the single price you enter. If prices are volatile, run it at a low and a high price to see the range of savings. Higher gas prices make an efficiency upgrade pay off faster.
Is it worth trading in a paid-off car just for better MPG?
Usually the fuel savings alone do not cover the cost of a newer car, especially with depreciation. Combine this figure with a true-cost-of-ownership comparison before deciding to switch vehicles purely for economy.