My Mazda 6 is also doing the same thing, and you are right...the smell is disgusting. I am actually taking my car to a different dealership next week, and I'll let you know what they say about it. I have filed a complaint with Mazda Corporate about some other issues, and I just recently received a survey about my most recent service visit. I sent it back with a 3 page letter about the lack of service I get when I take it in. Mazda is wanting to turn their customer satisfaction around, so I think people are gonna have to just start flooding them with enough complaints to get something done. It seems like their attitude completely changes once you've signed on the dotted line and the car is yours!!

 

I worked at a Ford dealership a hundred years ago. I think I remember something a that time about a rotten egg smell being atributed to one of the exhaust or oxyen sensors. Can't quite remember which one, but wouldn't hurt to have a scope put on it even at this early stage (parts CAN be bad right from the factory).

 

You can also get a pretty nasty smell from a burnt up clutch. Is your car stickshift? Do you drive with your foot on the clutch pedal? Driving with your foot on the clutch pedal (or brake pedal for that matter) can cause excessive wear of the clutch (or brakes) Overheat either and you'll get a pretty good smell.

If you're burning oil, you'll get blue smoke along with the smell.