I had an issue similar to your situation. I had the X for 9 months with 12k miles i put on it. The dealer shown me a clean Carfax when i purchased it, later i discovered Autocheck shown accident. The diminished value was $9000 for my X. I contacted the dealer for the possible lawsuit against them for 2 months, with many legal research and advices from internet, finally they agreed to repurchased the truck back and refunded me my full purchase price. You should first contact Carfax for clarification, and want to know their policy as to how long they have to list the accident once the police report filed, also you want explanation to your case. If it does not come to your satisfaction, your next step should be the dealer, contact person with decision making, like GM, or owner. I think someone is responsible for the diminished value here. If you need a free legal advice, then go to AVVO.com and post your question in detail. or you can contact a local consumer fraud attorney for a free consultation, and if they willing to take your case, it will be on contingency basis, that is how it work for auto fraud, if it is a fraud case. If attorney advice you that you have a strong case, and if you want to pursue the matter yourself, then pm me and i will tell you what i did during my entire complicated and frustrated issue.