Hi wasp,
First of all, sorry to hear this. From experience I'd say that even if the offending driver is identified, I'd suggest that there are all sorts of reasons why he may end up paying nothing, i.e. he has no insurance, the car was stolen etc etc.
A Court can order someone to pay but cannot compel them if they decide not to. You have the option of a private prosecution but that would cost your g/f, and again there is no guarantee of receiving any cash.
If the offending vehicle is identified, there is an organisation called the Motorists Insurance Bureau (MIB) which deals with
uninsured driver claims.
Your g/f's insurance co should be able to advise her further. Get her to make sure that they are liaising with the Police and make sure that they keep her informed.
Good luck.