The contact owns a 2013 Mercedes-Benz C300. The contact stated while his wife was driving approximately 30 mph, she was depressing the brake pedal and the rear side of the vehicle shifted to the left independently, causing to impact with another vehicle. The contact stated no warning light was illuminated. The air bags did not deploy. The contact stated no one was injured nor sought medical attention. A police report was filed. The vehicle was drivable and the driver was able to continue driving to her destination. The contact took the vehicle to an independent mechanic and was informed the sub frame was corroded. The vehicle was not repaired. The contact called the local dealer and made them aware of the failure. The vehicle was not repaired. The manufacturer had not been informed of the failure. The failure mileage was approximately 50,000.