CAR DEFOG FAILED AT NIGHT IN HIGHWAY IN A HEAVY RAINSTORM. DRIVER AND PASSENGER UNABLE TO SEE LANES OUT OF ALL WINDOWS. APPRIXIMATE SPEED WAS 100 K.M. THIS OCCURRED DURING A WARM SUMMER MONTH. DRIVER ALMOST CRASHED CAR AND ENDED UP IN A DITCH ON ROADSIDE AFTER NOT SEEING CURVE IN ROAD.