Finance
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021 Auto Leasing
Most disagreements between a shopper and a dealer over a car loan are not arguments about money. They are vocabulary mismatches. This glossary defines each Reg Z disclosure field and the operational math behind it, with the references that govern the term.
Fast answer: a glossary plus the math
Most disagreements between a shopper and a dealer over a car loan are not arguments about money; they are vocabulary mismatches. "APR" and "interest rate" are not the same. "Amount financed" is not the same as "vehicle price." "Total of payments" is not the same as "monthly times term." Reg Z (12 CFR Part 1026) defines each of these terms precisely and requires their disclosure before consummation. The FTC's financing-or-leasing-a-car page summarizes the same disclosures in plainer language.
This glossary covers the terms that appear on a typical retail installment contract for a vehicle purchase, with the math behind each. Each entry names the regulator-defined meaning, the operational implication for a shopper, and the place on a contract where the term will appear. The point is not memorization. It is fluency. When a shopper can read each Reg Z disclosure line and know what it does, the worksheet conversation collapses from a sales pitch into a comparison.
APR vs interest rate
The interest rate is the cost of borrowing the principal, expressed as a yearly rate. It is the rate the lender uses to compute interest on the outstanding principal each month. The APR is the cost of credit expressed as a yearly rate that includes the interest plus most loan fees imposed as a condition of credit. Reg Z defines both, separately, and requires APR to appear on the disclosure. The CFPB's understand-your-loan page covers the difference in plainer language.
Two consequences follow. First, the APR is the comparison anchor across loans of similar shape, because it puts interest and fees into one number. Two loans with the same interest rate and different fee structures can have meaningfully different APRs. Second, the APR alone is not enough to rank loans of different shapes. A 60-month and an 84-month loan at the same APR on the same vehicle produce different total of payments, because longer terms accumulate more interest dollars even at the same APR. Compare APR across loans of similar shape, and total of payments across loans of different shape.
A common subtle point is that the APR appears as a yearly figure, while the interest is calculated monthly. The dealer's worksheet should make the math visible. If the APR and the resulting monthly do not reconcile to the standard amortization formula at the disclosed amount financed and term, ask the dealer to show the calculation. Most discrepancies are arithmetic; some are fee-treatment choices that can be challenged. Either way, the disclosure has to be self-consistent.
Amount financed and what gets capitalized
Amount financed under Reg Z is the principal you actually owe after prepaid finance charges and any cash paid. In a typical retail installment contract, amount financed = vehicle price + capitalized add-ons + capitalized prior negative equity + any other capitalized fees - down payment - net trade-in (or - trade-in equity, if positive). Each line in that math is on the contract; the amount financed appears on the Reg Z disclosure as a single number.
Three things commonly get capitalized that shoppers may not notice. Optional add-ons (GAP, service contracts, credit insurance) financed into the loan rather than paid separately. Prior negative equity, where the trade-in is worth less than the existing loan payoff and the gap rolls forward. Dealer or lender fees treated as financed rather than paid at signing. CFPB guidance is explicit: each one increases the amount financed, the monthly payment, and the total cost of the loan. None of them is necessarily wrong; all of them should be visible at the comparison stage so the shopper can decide whether to capitalize each.
The Reg Z disclosure does not break down amount financed into its components by line; the contract itself does. The cleanest review is to read the contract's itemization next to the amount-financed line on the disclosure. Anything in the itemization that the shopper did not consciously agree to capitalize is worth flagging before signing. CFPB's complaint portal handles cases where a shopper signed something they did not see; the better path is to see the components first and decide whether to capitalize each.
Term length and total interest
The relationship between term and total interest is mechanical, not lender-specific. The same amount financed at the same APR over a longer term produces a smaller monthly payment and a larger total of payments. The reason is that interest is calculated on outstanding principal each month, and a longer term has more interest-bearing months. Federal Reserve G.19 has shown nationwide auto-loan terms drifting longer over time, which has changed the average shape of the market without changing the per-loan math.
CFPB's understand-your-loan and shop-for-an-auto-loan pages emphasize total-cost comparison precisely because the term-versus-monthly tradeoff is so easy to misread. A common shopper mistake is to compare a 60-month loan and an 84-month loan on monthly payment alone, conclude the 84-month is "cheaper," and miss that total of payments is meaningfully larger. The 84-month loan is not "wrong"; it solves a different cash-flow problem. But it is not cheaper.
A useful sanity check is to compute total of payments at the term you are considering and at one term shorter and one term longer. The three numbers tell you how much each step in term costs. Sometimes the marginal cost of a longer term is small enough that a shopper happily accepts the cash-flow benefit; sometimes it is large enough that a shopper switches to a shorter term and a different vehicle to keep the monthly inside their budget. Either decision is reasonable. The point is to make it consciously, with the math visible.
Down payment and trade equity
Down payment is the cash a shopper pays at signing that reduces the amount financed. Trade equity is the difference between the trade-in value and the loan payoff on the trade-in vehicle (if any). Trade equity can be positive (the trade is worth more than the payoff, which reduces the new amount financed) or negative (the trade is worth less than the payoff, which increases the new amount financed when rolled forward). CFPB calls out negative equity as a recurring risk because the new monthly can still look acceptable while the new total of payments shifts up by thousands.
The FTC's negotiate-separately recommendation applies directly here. Negotiate the vehicle price first. Then negotiate the trade-in second, which exposes the actual trade-in value the dealer is offering. Then evaluate the financing third, against an outside preapproval if possible. When all three are combined into a single monthly, you cannot tell which lever moved when the deal changes; a "lower monthly" can come from a higher trade-in value offset by a higher vehicle price, with the same total dollars in your pocket.
A practical decision is whether to put down extra cash at signing or finance the full amount and keep the cash. There is no universal answer. CFPB's understand-your-loan page treats it as a borrower preference. Putting more cash down lowers the amount financed and the total of payments at the same APR. Keeping the cash preserves liquidity and may earn returns elsewhere. The right answer depends on the shopper's other financial uses for the cash and on the loan's APR relative to alternative uses of the same dollars.
Fees: dealer, lender, registration, and tax
The fees on a retail installment contract come from four sources, and a careful disclosure separates them. Dealer fees are charged by the selling dealer: documentation/processing, dealer-installed-equipment markups, dealer-supplied add-ons. Lender fees are charged by the financing institution: acquisition fees, doc-prep fees, late-fee structures. Registration fees come from California DMV: vehicle license fee scaling with vehicle value, base registration, weight-related components. Tax comes from CDTFA and is generally collected on the full purchase price at registration on a financed purchase.
Reg Z requires fees imposed as a condition of credit to be in the finance charge. Other fees (registration, tax) typically sit outside the finance charge and inside other line items on the contract. The line between "finance charge" and "non-finance fee" is regulator-defined, not negotiable. A worksheet that bundles everything into a single "fees" line is not necessarily wrong, but it is not directly comparable to a worksheet that itemizes each. Asking each lender or dealer to disclose dealer fees, lender fees, DMV registration components, and tax separately is the same fair ask across all of them.
Two practical tests: the registration line should reconcile to the DMV fee calculator output for the same vehicle, and the tax line should reconcile to the applicable tax rate against the full purchase price. Discrepancies are worth flagging in writing rather than absorbing as "normal dealer fees." Most are paperwork-level. Some are fee-treatment choices that can be challenged. Either way, the disclosure is more useful when each line is visible.
Frequently Asked Questions
Is APR the same as interest rate?
No. The interest rate is the cost of borrowing the principal, expressed as a yearly rate. APR is the cost of credit as a yearly rate that includes interest plus most loan fees imposed as a condition of credit. Reg Z defines both separately, and the APR is the comparison number across loans of similar shape.
What is 'amount financed'?
Reg Z defines amount financed as the principal loan amount minus prepaid finance charges and any cash paid. If you finance add-ons or roll prior negative equity into the new loan, those amounts increase the amount financed and therefore the total of payments.
Why is 'total of payments' on the disclosure?
Total of payments is the sum of every scheduled payment over the loan term. CFPB guidance recommends comparing this number across offers because it captures total cost. APR alone can hide cost shifts that show up only when the term changes.
Are dealer fees the same as lender fees?
No. Dealer fees are charged by the selling dealer; lender fees are charged by the financing institution. California DMV registration components are separate from both. The dealer worksheet should label each line so you can see which entity charged which fee.
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