if mercedes insurance will deal with it, that's the best scenario because your personal insurance will not necessarily raise your rates since you aren't forcing them to pay anything. the next best option is to have your insurance company deal with it because they will front the money for your medical expenses (usually), and then use their own lawyers to figure out what they can recover from the other driver's insurance company. In the scenario when the other driver is completely at fault, many insurance companies representing your interests will also attempt to recover the deductible you had to pay. I got smashed last year, and we had to pay a $500 deductible. It was totally the other guy's fault, so my insurance company paid for our repairs, and has been going after the other guy's insurance for reimbursement. If successful, they will return our deductible.
edit: however, your insurance company lawyers will limit their exploration to recovery of damages they had to pay for bills. If you are looking to get a payday civil judgement, your insurance company will not be able to help you with that - you'll have to retain a litigator that handles car accidents (the billboard ambulance chasers), and sue for pain and suffering, mental anguish, all that crap.