If this is a criminal case involving restitution or a civil case, you are entitled to loss of use of the vehicle but may not be able to receive interest from the time of the accident. You are possibly entitled to interest on any money you paid for repairs from the time you made the payment.
Yes, you are entitled to reimbursement for both the cost of repairs and the loss of use (rental charges). Ask the Prosecutor and Judge to make payment of restitution as part of this guy's probation conditions imposed at sentencing. You will likely not get interest, unless you sue him in civil court, get a judgement, and interest runs on the unpaid balance. The interest will be minor. I would use the restitution-as-part-of-probation strategy if the Judge will do it. Most will, some won't. Good luck!