Money

Why a price changes while it sits

A used car gets more expensive to own and less valuable to sell on the same calendar. Those two facts move toward each other a little every day, and the day they meet is the day the price on the windshield has to move.

Drive Thru Deals · September 17, 2026 · 4 min read

People read a price drop as a confession — the dealer got caught, the car has a problem, somebody blinked. Occasionally that's right. Far more often it is just arithmetic arriving on schedule. Here is the arithmetic.

Illustrative only. The shape is the point; the numbers are round figures chosen to make it legible, not a record of any vehicle. How steeply either line moves depends on the car, the season and the week.

The rising line

The largest, dullest component is interest. Inventory on a small lot is usually bought with borrowed money, and that money accrues daily, per car, from the day of purchase to the day of sale. It does not care whether anyone came in on Saturday.

The daily number is not mysterious. It is advance × annual rate ÷ 365. Put $20,000 in a car and pick any rate you like: at an illustrative 9% that is about $4.93 a day — roughly $148 a month, about $444 by day 90. Floorplan rates vary by lender, by dealer and by the week, so run it with a rate you have actually been quoted rather than ours or anyone else's. The mechanism is explained in Floorplan: the loan on the cars.

Interest is just the visible part. A car that sits also quietly consumes things:

Pushing cost up

Interest, daily, from day one.
Batteries. A car that moves twice in two weeks needs charging, and eventually needs a battery.
Washing and detailing. Not once. Every week it is outside.
Tires and brakes. Flat-spotted tires and surface-rusted rotors from standing still are real and sometimes get replaced twice.
Insurance and overhead on inventory, which accrue whether a car is selling or resting.
The space. On a six-car lot this is the big one. A slow car isn't occupying a parking spot, it's occupying one sixth of the entire business.

Pulling value down

Ordinary depreciation. The car is a year older every year, including while parked.
Comparable sales. Every similar car that trades somewhere else resets what yours is worth, and you don't get a vote.
Season. Convertibles and four-wheel drive do not have one price all year, and the calendar is not negotiable.
Model year rollover. On January 1 a four-year-old car starts being described as five years old.
Listing age itself. After a few weeks the photos read as stale and shoppers assume something is wrong. The perception is frequently false and it is still priced in.

Where the lines meet

Follow the drawing. At day zero there is daylight between what the car cost and what it is worth, and that daylight is the entire reason to be in business. Every week, the top line drifts down and the bottom line creeps up, and the daylight narrows. Somewhere out past day sixty on this illustration the two meet, and after that point holding the car is no longer slow — it is expensive.

Critically, the loss does not arrive as a dramatic event. It arrives at five dollars a day, which is precisely why it is easy to ignore. A dealer defending a price for three extra weeks is not being stubborn about $400 of margin. He is spending $100 to keep from admitting he was wrong about $400, and then doing it again.

So the price moves

Repricing is the correction. It is also, for us, a public one: the number is on the windshield and on the website, so there is nowhere to make the adjustment quietly. We drop it, the page updates, and anyone who looked last week can see exactly what happened.

That is uncomfortable and it is the honest form of the same decision every dealer makes. The alternative — leaving the advertised number high and discounting in the room, to whoever pushes hardest — produces the same average price and distributes it unfairly. The people who do worst under that system are reliably the people least willing to argue.

What this means if you're buying

Ask how long it's been here. It is a simple question with a factual answer, and the answer tells you where the car sits on that curve. A car at day five is at its stiffest, not because the dealer is greedy but because nothing has happened yet to make it otherwise. A car at day fifty is costing somebody money every morning.

A repriced car is not a worse car. This is the part most shoppers get backwards. The reasons a good car sits are usually boring — an unfashionable color, a trim level nobody searches for, a body style that is out of season, or the plain fact that on a six-car lot the right buyer for a specific vehicle may simply not have walked past yet. Meanwhile the reasons a car sells in four days include being underpriced by mistake. The published inspection is where you check which one you're looking at; the number of days is not evidence about the car.

And the honest catch: if a dealer reprices on a predictable schedule, a patient buyer learns to wait. We know that. It is a genuine cost of publishing the number and we would rather pay it than run the other system, where the price is a starting position and your savings depend on your appetite for conflict.

The question that surfaces all of this. "How many days has this one been on the lot?" — then look at the reconditioning record and the inspection, not at the calendar, to judge the car. The two facts answer different questions, and confusing them costs buyers money in both directions.

Every figure on this page is a round illustrative number used to show the shape of the arithmetic. It is not an accounting of any particular vehicle and not a quotation of any rate available to us or to anyone else. Interest rates, holding costs and market movement vary widely by car, lender, region and season.