The pollen filter could be the main cause of this bad odor. I believe for the first models, 98 year production, the pollen filter requires changing every 10,000 miles and that was changed to 20,000 for all models after that first year. Be sure to get the filter from VW parts..It is the same price as a Fram and is of much better quality than any after market brand I have seen. The Fram brand has a cheap frame around the filter and I could not see any charcoal layer to the Fram filter that is a must for completely cleaning the incoming air.You can change it yourself with the proper tools and directions... Another cause for bad odors is a contaminated A/C evaporative coil that lives inside the car in the heating and A/C module under the dash. When changing the pollen filter, turn fan on to about 1 or 2 and lightly spray some Lysol down into the opening until you think the coils are covered enough. Turn fan off and replace filter allowing Lysol to dry and decontaminate the coils. To avoid future odors that are caused by having excess moisture remaining in this area you should always use the A/C on recirculate(this is the most economical setting). This eventually dries the air out in the car so much that barely any moisture condenses. When finnished with your drive and A/C use, leave on recirculate when stopped and turn off A/C compressor and turn fan up to 3 or 4 for about 30 seconds or so and this will dry out any left over moisture. I do this every time I am finnished with a drive or A/C use, and I have enver had any odors from my A/C-heating areas. Good Luck, JK98beetle said:hi i am new to the beetle i just bought one last week its a great little car but i get some bad smells from the heat and vents i think i need to change the dust and pollen filter they talk about in the book but i dont know how can anyone help??