how much decrease because the car was rear ended

First, a couple questions. Was the vehicle repaired properly? Was the incident reported and does it show up on the Carfax? If it listed on the carfax this will negatively effect the value. I can't give you specific numbers, but it could be 10 to 20 percent less.

accident was not reported to police, just insurance companies (progressive and USAA). ML350 seems to have been repaired fine. Have no idea about Carfax reporting.

It may have been reported to carfax by the repair facility or the insurance company. Hope that helps! Jim

Thanks for that, but what, in your expert judgment would be a close amount that the value decreased on the car due to the accident

Any ideas on what the DV on my car might be?