I suggest you carefully consider your situations. You are involved in two suits, one you are suing the driver and the second, which you are really concerned about, the passengers in the truck are suing you.
First about the police report. In a heavy rainy days a police, especially when called afterwards, are often inclined not to issue any report such that each party will be responsible for his or her own damage. When there is a personal injury, the police might be obligated to issue report. But there must be some hard evidence to assign fault, knowing his report can be disputed. Now you may dispute the report, but the accident happened long time ago. Without some real evidence (not theory)to convince him, the police will not change his report. Such evidence include witness, photoes, among others. Police make mistakes all the time but changing the report is an entirely different story. You may find someone to do accident reconstruction, given there were injuries involved, but it would cost you $5000-$10000 and you may not necessarily like the result either.
Second about the suit that you are the defendant. The driver might be negligent, given he hit you from behind. And, you are correct that any fault in his part will reduce your liability in a pure comparative fault state. The problem is that you cannot impute his negligence in this case because he is not a party in the case. The case is about the passenger against you. Even if the driver was negligent, you cannot impute his negligence to the passenger, without proving some special relations such as joint venture. Now the driver is missing, the passenger can simply deny such relation and you cannot prove it. Now the only issue is whether you were at fault or not. It goes back to the police report. Without any other evidence, the police report is the only evidence and it will be sufficient for the plaintiff to meet his part of burdern of proof. To me, a simple denial is really weak. Except denying your fault, you could raise some defenses though. You cannot prove the driver was negligent because one, the police report, two, that does not mean you were not at fault, and three, irrelevancy.
Third, the plaintiff may falsified the medical bills. You will need expert testimony to prove he was not injured or did not need such expensive therapies. Expert witness would charge hundreds of dollars each hour they testify, with court appearance extra.
I seriously think your best way to handle this is to find an attorney in your area who is specialized in car accident, find out how much the plaintiff really spent, make a bona fide offer to settle.
Disclaimer: the above answer is a reply to a question posted on an internet public forum. It does not constitute a legal advice, should not be relied upon, and does not create any attorney-client relation. The reader must understand the laws of each state are different; each case is fact specific; and it is impossible evaluate a situation without comprehensive consultation and review of all the relevant facts and law. There is no confidentiality on the part of the answerer given the question is posted on an internt public forum.
