VEHICLE WAS PICKED UP FROM A DEALERSHIP AND DRIVEN FOR APPROXIMATELY 20 MINUTES TO HAVE EMISSION SYSTEM CHECKED. WHEN HOOD WAS RAISED FOR THIS EXAMINATION AN ENGINE COMPARTMENT FIRE STARTED. AN EXAMINATION OF VEHICLE DETERMINED THAT FIRE ORIGINATED CLOSE TO BOTTOM OF ENGINE WHERE IT MET THE AUTOMATIC TRANSMISSION ASSEMBLY. POSSIBLE CAUSE WAS AUTOMATIC TRANMISSION OVERHEATING AND CAUSING A GROUP OF WIRES AND GREASE TO IGNITE. PLEASE PROVIDE ANY ADDITIONAL INFORMATION / DOCUMENTATION. NOTE: PRIOR TO THE FIRE, THE DEALERSHIP WAS EXAMINING THE FOR THE FOLLOWING PROBLEMS: ANTI-LOCK BRAKE SYSTEM, A HUB & WHEEL NOISE, AND A LEAKING EXHAUST MANIFOLD LOCATED CLOSE TO THE REAR DIFFERENTIAL UNIT.*AK