A VEHICLE WAS LEFT UNATTENDED ON A HILLSIDE IN DIRECT SUNLIGHT AFTER IT HAD ALREADY HIT A MAILBOX. I STRUCK VEHICLE IN LEFT REAR WITH MY RIGHT FRONT IT TOTALED BOTH VEHICLES. I WAS DRIVING ABOUT 50 MPH AND NEVER SEEN CAR PRIOR TO IMPACT. IT INJURED BOTH PASSENGERS IN BACK SEAT BOTH FRONT SEAT OCCUPANTS WERE NOT INJURED BUT AIRBAGS NEVER DEPLOYED. *TR