SLOWLY PULLING OUT OF NARROW PARKING LOT EXIT LANE, THROUGH OPENED GATE. RAPID UNEXPLAINED ACCELERATION, SEEMED TO LAUNCH CAR ACROSS ONE WAY CITY STREET INTO RESTAURANT BUILDING. PASSENGER SEAT BELT (FASTENED, LEFT BRUISES) RELEASED UPON IMPACT; PASSENGER DASH BOARD AIRBAG DID NOT DEPLOY; DRIVERS' AIRBAG WEAK. PASSENGER HOSPITALIZED FROM LOWER AIRBAG, BROKEN LEG, SEVERE LACERATION.