I'm looking buy new mirror caps for my '08 non-S. I've noticed that there are two cap styles - those for "folding" and for "non-folding" mirrors. Is this referring to people who have/don't have power folding mirrors, or mirrors that do and do not fold at all?

I have manual fold-in mirrors, not power folding ones. I'm guessing I'm categorized as non-folding?? I just want to make sure I buy the right caps

 

you are correct in your thinking.