why did instant market value change on car I was looking at?

Understand that, but why a change in a few days in a zip code where there are very few of these cars (if any) selling? Can dealers change the instant market value?

It may also reflect the vehicles coming through auction and the profit margins that dealers expect to make. If you really want to save on a lease return ride like the e60 Sportwagen, know you needs and the vehicle, then go to the auction with them. For $500 you can save thousands.

Hmmm...Interesting! 1. How did you know it was a lease return? 2. If you're not a dealer, how can you go to the auction with "them" as you suggest?

Make friends with a used vehicle dealer. I have several that are "old friends of the family". If you have the personality, ask for the used car manager and make friends. Tell him what you are looking for. You might get an invitation to tag along.

If a seller tweaks the options on their listing, the market price will change.