WHILE MERGING ONTO THE FREEWAY, I WAS TAKING MY CAR TO BE SMOGGED. AT SPEED, I NOTICED A LITTLE WHITE PUFF OF SMOKE EMIT FROM THE RIGHT SIDE OF THE ENGINE BAY. AS I PROCEEDED TO START MOVING TO THE SHOULDER, THIS PUFF HAD TURNED INTO A GRAY PLUME. AS I FINALLY REACHED THE SHOULDER, THE ENTIRE FRONT OF THE ENGINE BAY WAS BILLOWING BLACK SMOKE. AS I TRIED TO STOP, THE BRAKE PEDAL WENT TO THE FLOOR, SO IT SEEMED THE FIRE HAD BURNT THROUGH A BRAKE LINE. I MANAGED TO ENGAGE THE EMERGENCY BRAKE SLOWLY AND MANAGED TO STOP ON THE SHOULDER. OPENING THE HOOD, I FOUND A SMALL FIRE BURNING AT THE REAR OF THE ENGINE, BUT IN FRONT OF THE FIREWALL. I HAD NOTHING WITH ME, SO I CALLED THE FIRE DEPARTMENT AND IT WAS EXTINGUISHED. HOWEVER, BY THE TIME THEY GOT THERE, THE ENTIRE ENGINE COMPARTMENT WAS TOTALED BEYOND EXTENSIVE REPAIR.