Lost

I got a new car in May. So far I like it very much. I get great mileage.  I make a lot of use of the sun roof.  I like how it handles the road.  I like all the passenger space.  With the bright yellow color I never have trouble finding it in a parking lot.  I just have a couple complaints.  For some unknown reason, the front passenger seatbelt looks like it has been gnawed by mice at one spot on both sides of the belt.  I don't know what happened there but it looks very serious.  My second complaint is that it has lost the new car smell.  Not only has it lost the new car smell, that new car smell has been replaced with a smell, well, how do I describe this nicely?  Manure comes to mind.  Manure is nicer than other words.  I think the problem started this early winter when I had to use the defrost.  I never used the AC in the summer.  I have a sun roof so I had no need of the AC.  But to get the frost off the windshield the AC is used and that is when the smell started.  Maybe there is mold in a vent?  You'd think with all the heat I'm using that smell would go away but it doesn't.  New passengers smell it more than I do.  I guess I'm used to the smell.  I put an air freshener in the car so now it smells like spring rain AND manure.  Some people think the smell is slightly different than manure.  In either case, my car has definitely LOST the new car smell.