Roleez

This may sound strange to some, but the pickle-like smell may be attributed to an exhaust leak. I've seen this in my cousin's Toyota Sequoia on a hot 90 degree day where the back seat area smelled strongly like someone spilled bottles of Windex in the cargo area. Have you got any emission warnings from iDrive or a Service Engine Soon light?

kpf

On my old E39, I had the moonroof fixed because it was stuck open (when heavy rain started, of course). After that, when it was hot outside I always had a "vinegar" smell in the car. I learned that the silicon glue they used to seal the roof dissolves into acetic acid at higher temperatures causing that smell.
Was something fixed or glued or sealed on your car in the back seat area lately?

SoCalBimmer

I went to Vegas last week, where it was 114 degrees and on my way there I started to smell a weird smell in my cabin. I don't know what it is either. Now it happens all the time even in 80 degree weather. It only happens after my car is warmed up. I went to a muffler shop to check for exhaust leaks but they said they didn't see any. I don't know what it is. Coolent leak? It has a weird sweet kinda smell but also the kinda smell that give you a headache, really hard to describe.

asdf1122

I'm glad I'm not the only one! It only started becoming a problem lately when we had a heat wave.

It does have that kinda sweet smell you get when you have coolant leak on the engine block and it evaporates... I doubt it would be coming from the back seats though.

asdf1122

Honestly I don't know. I picked it up in January CPO so that might be the case. I guess I could call the dealer I bought it from and ask???

Thanks for the help.