PURCHASED A MERCEDES CLA 250C, AND HAVE HAD IT BECAME INOPERATIVE WHILE DRIVING ON THE BELTWAY IN WASHINGTON D.C. TRAFFIC, AND MORE RECENTLY ON THE I-5 IN SAN DIEGO ON 1/21/2017 DURING RAIN AT SPEEDS OF 60+ MPH IN HEAVY TRAFFIC. THE VEHICLE DECELERATED QUICKLY AND LOST SPEED. THE CONSOLE POPPED UP FLASHING MESSAGE 'PRE-SAFE FUNCTIONS LIMITED' ON THE CONSOLE. THE VEHICLE DID NOT RESPOND TO ACCELERATOR. AFTER COASTING TO THE RIGHT SHOULDER I WAS HIT, BY A PASSING CAR, AND THE MOTORIST KEPT ON GOING.THIS HAD HAPPENED ABOUT 10 TIME, AND I BOUGHT THE VEHICLE NEW. MERCEDES AWARE, YET THEY WOULD NOT DO ANYTHING BECAUSE THEY SAID IF THE ENGINE LIGHT IS NOT ON WE CANT DIAGNOSE IT. *TR