How OttoQuest prices cars

What the numbers are built from

Cars for sale: listings from dealers' own websites, dealer groups and marketplaces across the U.S., and private sellers, read every day and the busiest sources every hour. A car listed in several places is counted once, by its VIN.

Sold prices: recorded auction results and public sale records, kept apart from asking prices. A sold price is what a car fetched; an asking price is what a seller hopes for, so the two are never mixed in one figure.

Each VIN is decoded with NHTSA's vehicle database to the make, model, trim, body, engine and drive. Specs and fuel economy come from the EPA, and recalls, owner complaints and service bulletins from NHTSA.

Cars that leave the market: when a complete read of a source no longer finds a car, it is marked off the market on that day. Most of those cars were sold; a large share vanishing at once is treated as a reading problem, not sales, and held back.

How a market value is built

A value starts from the median price of cars like this one: the same trim and model year when enough of them are known, else the same model and year. Sold prices come first, then the last asking prices of cars that left the market, then current asking prices:

• same trim and year, sold (5 sales or more);
• same trim and year, last asking price of cars that sold or left the market (5 or more, from 3 or more sources);
• same trim and year, asking now (6 or more);
• the same three steps for the model and year.

Mileage

Each model year has its own mileage curve, measured on its cars: how much the price falls per mile. The value is moved along that curve from the typical mileage of the cars it was built from to this car's mileage, by at most 50% either way. When a car is far from every group's typical mileage (a 38,000-mile car whose trim mostly sells at 110,000), the value is marked rough and the car is never shown as a deal.

History, state and factory options

History: where a listing reports one accident, several accidents or a branded title (salvage, rebuilt, flood), the value is adjusted by a factor measured on the listings themselves, comparing cars with and without that history within the same trim and year. On the November 2026 listings, one accident takes about 1.5% off, several about 3% and a branded title about 14%.

State: the same car asks more in some states than others. Each state's factor is measured the same way, for each model where enough of its cars are for sale in the state and for all cars otherwise, and applied to a car's value in that state.

Factory options: where the car's window sticker is known, its options total is compared with the typical options of its trim and year. Options keep about a third of their sticker price, measured on the listings, so a car with $5,000 more options than usual is worth a little more, not $5,000 more. Single features (a sunroof, leather, CarPlay) move asking prices by under 2% each within a trim, so they are not priced one by one.

Deals

A car's deal figure is its asking price against its market value. Within 3% of the value is a fair price; more than 10% below or above is well below or well above the market. A price far below the value is a reason to ask why (fees left out of the advertised price, damage, a title problem) as much as a bargain.

How often it changes

Listings are read every hour for the busiest sources and every day for the rest. Values are rebuilt several times a day from the cars then for sale and the sales on record, so a value moves as the market does. Records of price changes and cars leaving the market start in October 2026.

What a value can't tell you

A value is a guide to the price, not to the car. It doesn't see condition, maintenance, tires or a history the listing doesn't report, and an advertised price may leave out dealer fees or require the dealer's financing. Have a car inspected, ask for the out-the-door price in writing and check its VIN for open recalls before you buy.

Data studies

The data guides are fixed snapshots: each states the day its data was taken, the number of cars, how they were chosen and how each figure was computed, and its table can be downloaded as CSV. Medians are used rather than averages wherever a few extreme prices could move an average.

Who pays for OttoQuest

OttoQuest is paid for by its members (OttoQuest Pro), not by dealers. No dealer pays to rank higher or to look like a better deal, and we don't sell shoppers' details as leads.

Questions

Public data

OttoQuest uses NHTSA and EPA data and information from the Washington State Department of Licensing’s Electric Vehicle Title and Registration Activity dataset (dataset), available under the Open Database License (ODbL, https://opendatacommons.org/licenses/odbl/1-0/).

See it at work: check a car’s price, value your car or read the data guides.