My response:
Take plenty of pictures - - close up, and from a distance, and from every conceivable angle.
Then, have two to three estimates prepared (if possible). If not, due to it's undrivable condition, then the one from where you have it repaired will just have to suffice.
Then, have the vehicle repaired. You are obligated, by law, to "mitigate" your damages by having the vehicle repaired so that it won't suffer any further damages by merely having it sit. Make sure you get a written opinion from the repair person as to how he believes the damage occurred; e.g., "this type of damage can only occur when someone forgets to screw on the lug nuts."
Since your son is an adult, prepare a "Promissory Note" for your son to sign and date. It's his promise to repay you for the cost of repairs. Remember, he's an adult, it's his vehicle, and he's the one who failed to have insurance. It's not your fault if you want to be nice and pay the damages while you're waiting to be reimbursed - - but, since you are, you certainly don't want him to "forget about" paying you back.
Once last point. If it turns out that an attorney won't take his case, he needs to consider filing a claim in Small Claims court and suing the mechanic for the cost of repairs.
IAAL
[Edited by I AM ALWAYS LIABLE on 02-12-2001 at 12:40 PM]
