RepairPal Certified shops can diagnose and repair your 2001 Mercedes-Benz C320. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
Im not sure you may have an axle problem,but i would check the wheel right away,the rattling may be a lug nut that has come loose and is rattling inside the hubcap.or maybe a wornout wheel bearing.