So my checker mirror caps are looking a bit yellow lately, and it's bugging me. Last week while I was at the dealer having a seperate issue looked at, I casually asked my SA if they typically replace the caps under warranty. He said they do not...

Not wanting to spend a fortune on new ones just yet, I'm wondering if anyone has any tips or tricks (short of painting them) to restore some whiteness to them?

 

Those have some sort of clear coat on them like the standard ones, right?

There might not be anything you can do, since they've needed wax their whole life to avoid fading/yellowing.

 

Start with a Meguiars #9 or similar 'swirl remover' detailing product. It should take off the oxidized paint, which is likely to be causing your yellowing. I know people have talked about 'freshening up' their bonnet stripes the same way.