IGNITION COIL FAILED ON HIGHWAY. CAR "SHOOK" VIOLENTLY UNTIL STOPPED IN PARKING LOT. ONCE CAR WAS OFF THE ROAD, THE COIL HOUSING CAUGHT FIRE. THE FIRE ULTIMATELY BURNED ITSELF OUT, AND THE CAR WAS TOWED TO THE LOCAL DEALERSHIP FOR REPAIR. THE DEALERSHIP NOTIFIED AUDI USA OF THE DEFECT AND RECOMMENDED VEHICLE REPLACEMENT. AUDI USA ELECTED TO REPAIR CAR UNDER WARRANTY. MULTIPLE FAILURES HAVE OCCURRED SINCE (SEE LIST). TS