WHILE DRIVING ON A CITY STREET I PUT THE CAR IN ECO MODE. THE CAR WAS MOVING AT THE TIME. I NOTICED THAT THE CAR SEEMED TO BE DRIVING LOUDLY. AS I TURNED LEFT, I SAW THE CAR WAS IN MANUAL MODE AND WAS IN FIRST GEAR. SO I TOOK MY FOOT OFF OF THE BRAKE TO SLOW DOWN THE CAR AND TRY TO PUT IT INTO DRIVE. AS I TRIED TO MOVE THE GEAR SHIFTER, THE CAR CAME TO A COMPLETE, SUDDEN STOP. IT FELT LIKE ALL FOUR WHEELS WERE SUDDENLY AND IMMEDIATELY LOCKED. I COULD NOT MOVE THEM, EVEN AS I HIT THE GAS. I DID NOT SEE ANY INDICATION ON THE DASHBOARD THAT THE EMERGENCY BRAKE HAD BEEN ACTIVATED. I HAD NOT FIDDLED IN ANY WAY WITH THE BUTTON THAT ALLOWS ME TO CHANGE TO ECO MODE OR WITH THE PARKING BRAKE. IN THE MOMENT IMMEDIATELY PRECEDING THE STOP, I HAD MY LEFT HAND ON THE STEERING WHEEL AND MY RIGHT HAND ON THE GEAR SHIFTER. THE PERSON BEHIND ME REAR-ENDED ME. THE DAMAGE TO MY CAR WAS MINIMAL. I HAD BEEN THE FIRST PERSON IN THE LINE TO TURN LEFT, SO THERE WAS NO ONE IN FRONT OF ME. I AM NOT SURE HOW I WAS ABLE TO GET THE CAR STARTED AGAIN. I THINK I TURNED THE STOP/START BUTTON A COUPLE OF TIMES. I LATER ATTEMPTED TO RECREATE THE AUTOMATIC STOP. BEFORE MAKING A LEFT TURN, I PUT THE CAR INTO ECO MODE. AS I TURNED, I SLOWLY RELEASED THE GAS AND SLOWLY BRAKED. THE CAR AGAIN CAME TO AN IMMEDIATE STOP, AS THOUGH ALL 4 WHEELS WERE LOCKED AT THE SAME TIME. WHEN THEN HAPPENED, I MANAGED TO GET THE CAR GOING AGAIN, AND THE NEXT TIME I PUT MY FOOT ON THE BRAKE, THE CAR CAME TO A SCREECHING HAL