I was driving my vehicle on the highway at approx 55 mph. Without warning my vehicleas engine failed and the vehicle went into neutral. I had to coast until the emergency shoulder was available as power steering was dwindling. As I pulled into the shoulder the wheel locked. The vehicleas engine could not be restarted and the vehicle was towed to the Cadillac Dealership. I feared for my life as cars were behind me at 55 mph or higher when my engine went out. I nearly didnat make it into the shoulder before the vehicle stopped completely.