Suzuki Repair: I purchased a 2003 Suzuki..., rotten egg smell, suzuki 4x4

Question
I purchased a 2003 Suzuki 4x4 Model xl-7 with a v-6 engine in June of 2003. This unit was loaded. I currently have 17,000 kms on it.
Yesterday I left on a business trip. About 3 hours into the trip, I could smell what was a sulphur (rotten egg smell) odour. It persisted for approximately 10 minutes and then disappeared. It happened again intermittently after that and today. It appears to be coming from the heat/air conditioning portion of the vehicle. Most times I have noticed it most when the air system is on automatic settings, on outside air and sometimes when the air conditioning light comes on. The last episode was so strong that I drove for 15 minutes at 0 degrees centigrade with the sun roof open.

Any thoughts or suggestions?  I phoned the service department at the dealer and asked the question. His comment was it must have been from the outside of the car, otherwise he could not imagine what it might be.

Thanks in advance for your response.

Rick

Answer
I live in a rather high altitude (1.8KM) cold (overnight lows of -25C quite common) mountainous area, and hear this every winter.  It is due to the fact that the vehicles are colder, the catalytic converter takes much longer to "light off", and it's efficiency is slightly down due to the cold weather.  If you're in traffic, it could well be the vehicles around you, or your own vehicle.  The service department at your dealer is most likely correct.  This isn't harmful, or even abnormal.  Just mildly annoying.  I think you will notice it doesn't occur when the ambient temprature rises again.