RETURNING FROM A LOCAL GROCERY STORE I DROVE INTO OUR GARAGE AND SHUT OFF THE ENGINE. IMMEDIATELY I HEARD A LOUD POP FROM THE ENGINE COMPARTMENT, LIKE FROM A FIRECRACKER, AND I SAW BLACK SMOKE COMING FROM THE HOOD AND FROM THE LEFT WHEEL WELL. I IMMEDIATELY TRIED TO RESTART THE CAR TO DRIVE OUT OF THE GARAGE. NOTHING WORKED SO I PUSHED THE CAR OUT OF THE GARAGE BY HAND AND RELEASED THE HOOD LATCH. BY NOW THE HOOD'S EXTERNAL SAFETY LATCH WAS SO HOT I COULD NOT RELEASE IT. WITH THE HOOD CLOSED, I WAS UNABLE TO EXTINGUISH THE ENGINE FIRE USING A 15 LB CO2 AND A 5 LB ABC EXTINGUISHER. THE CITY FIRE DEPARTMENT ALSO WERE UNABLE TO EXTINGUISH THE FIRE UNTIL THEY SAWED THE HOOD IN HALF. THE 2 1/2 YEAR OLD CAR WAS A TOTAL LOSS. A EXPERT FROM BMW OF NORTH AMERICA INSPECTED THE CAR REPORTING THAT WAS TOO MUCH DAMAGE TO DETERMINE THE FIRE'S CAUSE. BMW NA CALLED TO REPORT THE RESULT NOT THEIR INVESTIGATION AND SAY THAT NO WRITTEN REPORT WAS AVAILABLE, ONLY THE VERBAL VERBAL FONECON.