Use Depreciation Scenarios Instead of a Guaranteed Resale Value

Define the value you are estimating

Depreciation is the decline in an asset’s value over time. For a car, the amount you could actually receive depends on condition, mileage, demand, transaction method, and the timing of the sale. An advertised retail price for a comparable vehicle is not necessarily the amount a dealer would offer for yours.

Decide whether your comparison assumes a private sale, a trade-in, or another route. Use the same route for both vehicles unless you explicitly account for the different work, time, and costs involved. A single optimistic listing is not a valuation plan.

Keep purchase costs and resale proceeds separate

For a basic ownership estimate, subtract expected net sale proceeds from acquisition cost, then add operating expenses and financing interest over the holding period. Net proceeds should reflect costs required to complete the sale and settle ownership matters. Outstanding loan payoff affects the cash you receive, but it is not itself another measure of depreciation.

This distinction prevents a common confusion: a car may have lost value while its owner has positive equity, or retain much of its value while a large loan still exceeds the sale proceeds.

Build three illustrative outcomes

Suppose a vehicle costs $24,000 to acquire and is kept for four years. Hypothetical net resale proceeds of $16,000, $13,000, and $10,000 imply value losses of $8,000, $11,000, and $14,000. Spread across 48 months, those are about $167, $229, and $292 per month. These numbers are scenarios, not forecasts for a model or market.

If your decision changes completely between the middle and lower resale scenario, the purchase depends heavily on an uncertain future price. A less expensive vehicle or a longer planned holding period may deserve examination, but neither automatically solves all ownership risks.

Connect value loss to your actual use

Estimate annual mileage and the condition you expect to maintain. A business requiring heavy driving differs from occasional weekend use. Consider whether changes in your household could force an earlier sale, because the convenient holding period in a spreadsheet may not survive a move or job change.

For an existing car, ignore the historical purchase price when comparing options from today forward. What matters is its current sale value, future running costs, and likely future value. Money spent years ago cannot be recovered by choosing a particular replacement date.

Make uncertainty visible

Update the estimate using several comparable vehicles and, where available, genuine offers. Keep notes on mileage, trim, condition, and transaction type. A documented range is more useful than a precise-looking number with no clear basis.

• Use comparable condition and mileage.
• Distinguish trade-in offers from retail listings.
• Model more than one holding period.
• Separate resale value from loan payoff.
• Avoid presenting future sale proceeds as guaranteed money.