You should have been compensated for the vehicle separately, and whether the amount you will receive is enough for another vehicle or not is not really relevant to how much you should receive for your injuries. You are entitled to all past and future medical expenses, lost income and pain and suffering caused by the collision. I think it was a mistake to not involve the insurance since a private party is not going to know how to adjust a personal injury claim. At this point you could either insist that they submit it to the insurance company or consult a good Idaho personal injury attorney.
You need to hire a lawyer and get insurance involved. You are going to get totally taken advantage of with this scenario. They have insurance. They caused an accident. Thats what it is purchased for. Please do not go this route and hire a lawyer.
Attorneys who do this kind of work almost always agree to a fee measured as a contingent percentage, and many will "guarantee" the offer you already have to you, meaning the percentage will be taken only from the additional settlement or judgment you receive. For this reason, and for the reasons stated succinctly by Mr. Lassen, you should retain local counsel without delay. To find someone reliable, look for personal referrals from other clients whose cases were handled well, and so not put much reliance in the lawfirms that advertise heavily. There are Boise PI attorneys who occasionally post on Avvo, and would almost certainly appreciate your business.
Best wishes for a favorable outcome, and please remember to designate a best answer.
This answer is offered as a public service for general information only and may not be relied upon as legal advice.