I was driving my 8 today, and below 50 mph, especially at very low speeds, I hear a noticeable clattering/rattling noise sounding like it came from the passenger side front wheel. I took a look at it and couldn't see anything that looked strange. It got a good bit quieter when I let off of the throttle, but I still heard the noise even in neutral while coasting with the engine idling. The gear changes and clutch feel fine, everything feels fine besides the strange noise. Any ideas?

 

Probably the heat shield around your exhaust.

 

Here's a video of the problem occurring.

 

That is certainly the sound of loose metal, probably your heat shield as suggested. You will have to get under there (when it is all cooled down) and poke around with your hands to find what is loose. Also could be (but hopefully not) your cat coming loose inside.

 

I just ran to Lowe's and got 4 stainless steel hose clamps. I'll get under there today and see if it is the heat shield. If not, what else could it be? The cat coming loose is possible, but I haven't seen any CEL's, and would think that an increase in C02 would trigger one. We'll see. The noise is very concerning, but everything feels fine.

 

Hey did you ever figure this out my car has a similar sound. Although my heat shields don't seem to be loose. Was that the problem?