One problem related to ignition switch has been reported for the 1999 Audi A6. The most recently reported issues are listed below.
Flames started shooting out the driver's side vent on 1999 A6 sedan. While driving smoke began coming out of the ac vents then flame starting coming out of the driver's side vents. The driver was able to pull of and extinguish the fire. The consumer sustained a small burn while putting the fire out. The consumer looked on the NHTSA website and found a recall on the ignition switch (04v13300) but has not received a notice about the recall.