DRIVER PARKING VEHICLE INTO PARKING SPACE (<5 MILES/ HR) - BRAKE APPLIED, PREPARING TO SHIFT INTO PARK. VEHICLE ABRUPTLY ACCELERATED, UNABLE TO STOP MOTION USING BRAKE. VEHICLE HIT CURB AND PROCEEDED OVER EMBANKMENT, WITH VEHICLE STRIKING LOWER LEVEL PARKING PAVEMENT APPROXIMATELY 15 FEET BELOW AT 90 DEGREE ANGLE AND LANDING INVERTED (TOP ON PARKING PAVEMENT). VEHICLE SEVERELY DAMAGED, DRIVER WITH NON-LIFE THREATENING INJURIES - WEARING SEAT BELT. AIRBAG DEPLOYED WHEN CONTACTING LOWER-LEVEL PARKING PAVEMENT. DRIVER HAD PREVIOUSLY EXPERIENCED UNEVEN ACCELERATION AND REPORTED ENGINE-RELATED ISSUES TO DEALERSHIP APPROXIMATELY 60 DAYS (JUNE 9, 2018) PRIOR TO INCIDENT. VEHICLE WAS EVALUATED WITH NO DEFINITIVE CAUSE IDENTIFIED; LOW OIL IDENTIFIED AND OIL REPLENISHED. VEHICLE SERVED ROUTINELY BY DEALERSHIP AND MAINTENANCE SCHEDULE FOLLOWED SINCE PURCHASE.