I recently traded in a car for a used vehicle. A few days later it was hit by an insured drunk driver while parked. Can I sue for loss in value to car

You would be entitled to the costs of repair.  If the costs of repair are greater than the market value, then you would be entitled to market value.  If the vehicle is repaired, but its market value has been diminished nevertheless, there is an argument that you should be paid for that loss of value.  It is very difficult to prove, but it may be worth making the argument when speaking with the insurance company.