AT LOW SPEED (BACKING INTO A PARKING SPOT ON THE STREET) THE BRAKE PEDAL GOT VERY HARD AND THE VEHICLE WOULD BARELY STOP. I THEN DID NOT GO INTO THAT SPACE TO AVOID HITTING THE CAR BEHIND ME. I PULLED INTO A PARKING LOT ACROSS THE STREET. WHEN BACKING IN, I COULD NOT STOP (MOVING WITH CAR AT IDLE ENGINE SPEED). THE HITCH HIT THE CONCRETE WALL-HAPPILY NO DAMAGE DONE. WITH RESEARCH, I FIND THIS IS A COMMON PROBLEM THAT GM HAS NOT ADDRESSED. I USUALLY OCCURS AT SLOW SPEEDS OR STOP AND GO SLOW SPEED TRAFFIC. THIS IS UNPREDICTABLE AND VERY UNSAFE. THE VEHICLE IS A 2015 WITH ONLY 35,000 MILES. THE VACUUM PUMP (THE FAILURE) IS BOLTED TO THE ENGINE AND ENGINE-DRIVEN AND LUBRICATED BY ENGINE OIL WHICH PUTS MY ENGINE AT RISK. YET NONE OF THIS IS COVERED BY THE POWER TRAIN WARRANTY. THIS IS NOT A SLOW, BUT A SUDDEN FAILURE ITEM. VERY UNSAFE IF IT HAPPENS IN SCHOOL PARKING LOT PICKING UP MY CHILDREN, CHURCH, CLOSE SPACES (NEIGHBORHOODS, PARKING AREAS).