How We Calculate Your Estimate
A useful estimate starts with clear assumptions. Here is what goes into yours.
Vehicle data
Enter your vehicle name and efficiency. FuelEconomy.gov / EPA publishes fuel-economy and EV-efficiency data; NHTSA vPIC provides vehicle specifications and VIN information. These are reference sources you can consult, not automated inputs to this version.
Fuel & energy costs
Gas cost = miles ÷ MPG × price per gallon. Electric cost = miles × kWh per 100 miles ÷ 100 × price per kWh. Rates are entered by you; the defaults are illustrative. The U.S. Energy Information Administration publishes energy pricing data you can use as a reference. Your actual utility rate or local pump price may differ.
Depreciation
Depreciation equals purchase price minus the resale value you enter at the end of ownership. A resale value is pre-filled using a published retention curve for your selected vehicle class (sedan, SUV, truck, EV or luxury) over your ownership period — you can override it with your own research at any time.
Insurance
Annual insurance × ownership years. The starting premium is pre-filled from a published base rate for your vehicle class, adjusted by a state-level multiplier. It is not a personalized quote — replace it with a real insurer quote that reflects your coverage and driving history.
Maintenance & repairs
Annual budget × ownership years. The default is pre-filled from published averages by vehicle class and age bracket (0–3, 4–7, 8+ years) — electric vehicles use a lower base rate automatically. Adjust it if your vehicle's condition or service schedule differs.
Taxes & fees
Ownership treats these as upfront costs, and Loan payment calculations finance the entered fees. The default is pre-filled using your selected state's sales tax rate and average registration fee — adjust it if your locality or vehicle price bracket differs.
Financing
Monthly payment = P × r ÷ [1 − (1 + r)−n], where P is principal, r is APR ÷ 12 as a decimal, and n is the term in months. At 0% APR, payment = P ÷ n. Ownership includes only interest accrued while you own the vehicle, not principal, to avoid counting the purchase price twice.
Other comparisons
Trade-in: a starting value is estimated from your original purchase price, vehicle class and age using the same published retention curve as the ownership calculator, then adjusted by condition (excellent 1.05, good 1.00, fair 0.90, poor 0.75) and by how your entered mileage compares to the average expected mileage for the vehicle's age (12,000 miles/year assumed). You can override the estimated value with your own research (KBB, Edmunds, etc.) at any time. The displayed range is ±10% of the final result, an illustrative planning band, not a validated appraisal.
Lease vs. buy: lease payments + additional upfront costs + end fees, compared with buyer cash paid minus estimated vehicle equity after the same period. Equity is resale value minus remaining loan balance. Equal running costs are assumed.
EV vs. gas: purchase price minus entered verified incentives plus energy costs. Simple payback divides the EV price premium by annual energy savings when both are positive. This comparison excludes depreciation, insurance, maintenance, financing, taxes and charger installation.
Using your result
All figures are planning estimates. Actual costs vary with driving, local rates, financing, vehicle condition and the future market. Monthly ownership cost averages economic costs across the selected period; it is not a monthly cash-flow forecast or loan payment.
Last updated:
This date records the methodology revision, not a live data refresh.
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