general problems of the 2001 Mercedes Benz 240

At several points during a road trip this past weekend, my 2001 mercedes c240 suddenly died while cruising at highway speed. There was no indication of any problems with the car in the months leading up to this incidence. However, shortly after purchasing it, the same thing happened while driving on the interstate at highway speed. The dealer checked the car at that time but never took any corrective action. In the latest incidences this past week the stalling put me in immediate danger of being hit because they happened on a mountain road with no shoulder and no place to pull off to safety. Traffic coming up from behind around a blind curve would not have been likely to see me in time to stop. Fortunately, after each incidence of stalling I was able to quickly restart the car after coming to a complete stop. I have an appointment with the mercedes dealer in the morning in an attempt to fix the problem. As of now I have no indication of the cause. Until it is fixed, I consider the car too dangerous to drive on the highway.