I know this problem has been mentioned before although perhaps not recently. I am hoping somebody has an answer. I have a new Q40 AWD which is past the break-in period at 3,750 miles. Since the AWD has been engaged over the winter, I have noticed a burning odor coming through the heating vents, particularly at slow speeds or idle. The origin seems to be from the rear of the engine compartment, near where the battery is located. This also has been occurring after highway speeds have been reached and the engine is warm. I have been to the dealer twice and they find no leaks and checked the front diff fluid which is up to spec. They attribute the problem to "new car smell" during which time a coating is burning off from the exhaust system. I think this is nonsense since the car already has 3,750 miles. Has anyone been to the mechanic for this problem recently on a G37x or Q40 AWD? I am not happy about breathing potentially noxious fumes in the cabin from this brand-new $40K car. Thanks.

 

It's possible that there is something on a hot part like the exhaust that is burning off and producing the smell but I would have 2 issues with that:

First, you have 4,000 miles on the car. Anything that would have been burning off should be burned off by now.

Secondly, by your post, it sounds like it's just started happening this winter.

Bring it back to them and tell them you want them to take a ride with you on the highway and see if they smell it. Don't leave without a better answer than burning exhaust coating.

 

I'd bet you just smelling assembly oils burning off various parts. Try changing your intake from outside air to recirculation of cabin air, see if that helps. If that doesn't help after a week or so return to your dealer and have them check it out and possibly change a saturated cabin air filter.

 

From my experience with a "burning smell", it's usually the winter melt splashing up on my exhaust and evaporating.

 

That happened to me yesterday. Scraped the underside on snow and ice pulling into an unplowed driveway. For a while thereafter, something smelled wrong. Just wrong.

God damn winter.

 

It's a pretty awful smell. However, I've come to live with it. It's all part of living in a winter city. lol.

 

I met a factory specialist (DTS) at the retailer this morning regarding the burning odor that has been persistent. He put the vehicle on the lift and found a leak in the drive shaft (this is a brand-new vehicle)! As it is spinning, a slow leak of grease is leaking onto the manifold and burning off! He says that it was either over-packed with grease by the factory, or there is a small break in the seal. Finally, a resolution to this problem. If anyone else experiences the same phenomenon, I suggest you look into this.

 

Good for you for being persistent. I would have chalked it up to winter slop getting onto the exhaust system and left it at that. Let us know whether it was a bad seal or excess grease.