So someone hit your car in the parking lot and you dont know who right? And you mean you want to file a claim with your own insurance company for the damages? In that case, do you have a comprehensive/collision coverage? If not, you have no claim. If yes, how much deductible do you have? $500 or $1000? If your deductible is more than $800, it does not make sense to file a claim. However, if your deductible is less than $800, you may file a claim but remember depending on the state you reside in, your insurance company can raise your premium anytime a loss is occured to them regardless of fault. You may not see the rate increase right away but next time when you renew your policy there is a possibility of higher premium. Now, its upto you to consider the cost vs benefit. If you have a $500 deductible and the cost to repair the damages is $800, they are just paying $300. You will have to pay $500 out of your pocket. And is that $300 worth the higher premium you may have to pay in future? Think and decide.