Thanks for your comments. The MB dealer in Ohio, where the incident occurred, reported no diagnostic code. Incidentally, the computer display in the car showed no malfunction at the time of the incident. The dealer hooked a fuel pressure gauge to the car and drove it for over 100 miles just to try and get a reading or to see if the problem would recur - nothing. I'll definitely bring it in to my dealer here in Chicago. Thanks again.
A friend reported a similar problem on a another model (also new). She was told there was a known problem with a "fuel sensor" - ever heard of that?