I WAS DRIVING SOUTHBOUND IN THE LEFT LANE ON I-495 FROM MD INTO VA, ABOUT TO GET TO THE EZ PASS CAMERA. I SELDOM USE THE PASS, THEREFORE IT IS NOT AFFIXED TO THE WINDSHIELD. I HAD PLACED IT ON THE DASHBOARD IN ANTICIPATION OF THE UPCOMING CAMERA. TRAFFIC WAS ALTERNATELY SLOWING DOWN AND SPEEDING UP TO APPROXIMATELY 35 MPH. THE DRIVER AHEAD OF ME SUDDENLY SLOWED NEARLY TO A STOP, SO I PRESSED MY BRAKES, WHICH CAUSED THE EZ PASS TO SLIDE ACROSS THE DASHBOARD AND UP AGAINST THE WINDSHIELD. UNABLE TO REACH IT WITH MY SEATBELT ON, AND BECAUSE THE CAR WAS BARELY MOVING, I UNFASTENED THE SEAT BELT TO RETRIEVE THE PASS. AT THE SAME TIME THE DRIVER AHEAD OF ME SLIGHTLY INCREASED HER SPEED, THEN SUDDENLY SLOWED AGAIN, WHICH I DID, TOO. HOWEVER, THIS TIME I HAD TO PUNCH THE BRAKE. IT WENT STRAIGHT TO THE FLOOR, MY CAR SPED UP, AND I WAS UNABLE TO AVOID REAR-ENDING THE CAR AHEAD. IT WAS SUCH A HELPLESS FEELING TO TRY AND STOP AND HAVE NO BRAKES! A "CRASH MODE" MESSAGE SHOWED UP ON SCREEN BEHIND THE STEERING WHEEL AND THE SYNC SYSTEM AUTOMATICALLY DIALED 911. THE OTHER DRIVER GOT OUT OF HER CAR AND WALKED BACK TO ASK IF I WAS OKAY. I WAS FINE, BUT BECAUSE TRAFFIC IN THE RIGHT LANE WAS SPEEDING PAST, AND SOME CARS WERE EVEN PASSING US ON THE SHOULDER, I DID NOT ATTEMPT TO GET OUT OF MY CAR. EVENTUALLY THE STATE POLICE, EMTS AND A TOW-TRUCK ARRIVED. MY STEERING NO LONGER WORKED, BUT ONCE THE OTHER CAR WAS TOWED OUT OF THE WAY THE RESPONDING OFFICER WAS ABLE TO WALK ALONGSIDE MY CAR, PUSHI