The OP already told us he filed suit in small claims and won a judgment which the Insurance Company paid for (property damage done to his vehicle). The remaining claim as a result of the hit and run accident has yet to be decided. These are 2 separate claims out of one incident! Now as often happens, someone may have 2 separate claims being litigated and they may be enjoined by the court so the claims can be more conveniently litigated, but in this case, the property damage claim has already been decided! Has nothing to do with Res Judicata--at all!
As far as the Defendant (the hit and run driver who was at fault), if he wants to attempt to sue the OP/OP's Insurance for his damaged vehicle, he has the right to do so, but it would be a waste of time because everything points to him as being the person at fault, so he surely isn't going to be compensated for his damage when he was the one who caused the accident in the first place.
There is NO RES JUDICATA--because there were no claims re-litigated--period! sheesh--can't you see that?