The book value of a car is the amount that a car is worth as estimated by an independent price guide, such as Kelley Blue Book; the car rating organization publishes used car prices based on data collected from a nationwide network of dealerships. Kelley Blue Book updates its listings regularly to reflect the current car market in the United States.
Kelley Blue Book lists the estimated listing prices for used cars, which are the prices that dealers report as the initial asking price of a car before its sale. While these listings are accurate and reflect the average from a broad spectrum of dealers, they don't include the selling price, which can be much lower depending on the specific dealer.
Kelley Blue Book has an online platform with values of new and used cars, tools to check a car's history and calculate financing costs, and links to partners who can provide insurance and loans.
Another feature of the online resource are tools to calculate the "real" cost of financing with a loan, considering out of pocket expenses like fuel and insurance as well as interest rates and the terms of a loan. Different cars and their "cost-to-own" price can be compared side by side using this resource.