Comprehensive Guide
Learn more in our Loans & Mortgage Guide.
How it works
A dealer rate markup — the industry calls it dealer reserve or rate participation — is the spread between the buy rate a lender actually approved you for and the higher contract rate the dealership writes on your paperwork, with the difference rebated back to the store as compensation for arranging the loan. It is legal, disclosed only in fine print, and invisible unless you ask: nothing on the four-square worksheet separates the lender's price from the store's surcharge. The mechanics matter because the markup compounds silently. This calculator prices it in dollars: enter the amount financed, the rate your credit union or pre-approval quoted, and the rate that appeared on the contract, and it returns the added monthly amount, the total extra interest across the term, and the markup as a share of what you borrowed. A two-and-a-half-point spread on a $28,000, 60-month loan is about $36 a month — nearly $2,150 in total, roughly 7.7% of the amount financed, pure negotiation room. The defense is structural rather than rhetorical: arrive with outside financing already approved, make the dealer beat that rate in writing, and treat any payment quote that skips the rate as a signal to slow down.Formula
Extra interest = (payment at contract rate − payment at buy rate) × term | Markup % = extra interest ÷ amount financed
Tips
- Secure a credit-union pre-approval first — it sets the ceiling the dealer must beat.
- Ask for the buy rate in writing; lenders cap markups near 2–2.5 points.
- Negotiate price, then rate, then term — never a single monthly number.
- Watch for the markup returning as 'approval fee' or bundled add-ons.
- Refinance later if stuck: a post-sale refi to the buy rate recovers most of it.