Car dealerships are one of the last retail environments built entirely on information asymmetry. The dealer knows: invoice price, holdback (manufacturer rebate to dealer), incentive programs, floor plan costs, and your credit score before you sit down. You know: the sticker price (MSRP). That's it.

The "four-square" technique: the dealer presents four numbers on a worksheet — trade-in value, purchase price, down payment, and monthly payment — then adjusts them simultaneously. Lower monthly payment? They extended the loan to 84 months. Better trade-in value? They raised the purchase price. The numbers are interdependent, and the dealer controls all four.

The F&I (Finance & Insurance) office is where the most profit is extracted. After you've agreed on a price and mentally committed (sunk cost), the F&I manager presents: extended warranty, GAP insurance, paint protection, fabric coating, tire warranties, and VIN etching. These products have 50-300% markups and are the highest-margin items in the entire dealership.

The defense: research invoice price on TrueCar/Edmunds before visiting. Negotiate one variable at a time (never the four-square). Get pre-approved financing before visiting (you're negotiating with your rate vs their rate). Say "no" to every F&I product (or buy them independently at 30-70% less). The strongest position: "I have pre-approved financing at X%, here is my target price based on invoice + $500, and I'm getting quotes from 3 dealers." The entire information asymmetry collapses.