Vehicle EconomicsCost of Driving More Miles
Your average cost per mile blends in the fixed costs you'd pay anyway. The next mile you actually drive costs something different, this isolates it.
Why this comes up
A new job with a longer commute, a road trip, or just driving more than usual raises a specific question: what does that extra mileage actually cost, not what your car costs to own overall. Your average cost per mile includes fixed costs like insurance and registration that don't change no matter how much you drive, so it overstates the real cost of one more mile.
How we calculated this
We compute fuel cost per mile from your MPG and gas price, then add only the costs that genuinely scale with mileage: marginal maintenance, tire wear, and an optional depreciation-per-mile estimate. Fixed costs like insurance and registration are deliberately left out.
Worked example, using this page's own defaults (2,000 additional miles, 28 MPG, $3.50/gallon): the added cost comes out to a modest per-mile figure well below what a full average cost/mile calculation would suggest, run the calculator above with your own numbers.
What this means
- Fixed costs like insurance and registration should never be allocated into a marginal answer, that's why this number is usually lower than Vehicle Cost Per Mile's average figure.
- If you're deciding between two vehicles with different MPG for a specific added-mileage scenario, this is the number that actually changes with the decision, not the average.
- This works the same for a one-time road trip or a permanent increase in your commute, just adjust the additional miles entered.
Limitations
Marginal maintenance, tire, and depreciation rates are your own estimates, not a universal per-mile wear rate. See Methodology.
Methodology
This engine is built on Vehicle Economics' fuel and charging cost model: your own miles, MPG or kWh, and rates converted directly to a dollar cost. See Methodology for the full detail.