I have an '08 Grand Cherokee Laredo, 3.7L V6 with 74,000 miles on it. Recently the exhaust/muffler have been getting loud, and during my state inspection the guy said it would probably need a new muffler/pipe in the next few months. That was about a month ago. Since then there has been an on-and-off horrible plastic/chemical smell in the cabin some of the time. My wife drives it about an hour to work each way, and she says sometimes it gets so bad she has to open the windows (in 20 degree temps…) or she gets a headache. She describes it as a “formaldehyde smell” and says it tastes kind of sweet. To me it’s more like a burnt plastic/chemical type odor. I checked all underneath but saw no plastic bags or anything else odd. Nothing unusual under the hood. No visible smoke. I have an appointment in two days to have the exhaust fixed. My question is - is there any way this weird smell could be exhaust related? I am hoping so, because otherwise it’s a total mystery. It’s definitely not an “exhaust” smell as I know it.