car cut off when driving on freeway

Will the car start after it cools down? If so, the problem is most likely the crankshaft position sensor.

My ML 500 just needed the crank sensor to repair same symptom

Hope you are as fortunate as the others who replied. Mine has been doing the same plus intermittent stalling or not starting from stop for a while. Crankshaft sensor was repaired and battery replaced by Mercedes who also found a bunch of other things to repair. Ran up a nice total of over $2000. Less than 2 week later it petered out again. They towed it back over 50 miles to their dealership, cleaned the posts, tried to diagnose the problem...told us a lot of things it wasn't, never said what the problem WAS. (obviously not only the crankshaft sensor in our case). This time the car ran well for a little longer....say 3 weeks, then stopped right before making it into a parking spot. Now they want to put in a Mercedes battery and casing for >$700. Um...how about "no". I called MBUSA & am dealing directly with them at this point. We'll see what happens.