Just bear in mind on the metallic powder filaments (bronzefill, copperfill, brassfill, etc) that the material is weaker than standard pla.
While it looks like metal when polished, the metal powder is giving no real structural strength to the material. It's just bits of metal embedded in plastic.
The stuff is a LOT weaker than standard abs or pla.

As far as all the negative things I've heard about pla goes. So far I haven't encountered a single one of them.
hell it doesn't even get soft in hot sink water - like it's supposed to.

Which given that I have a roll of white pla that won't even extrude at anything less than 210c - doesn't actually surprise me.

The supposed lower limit on most pla I've got is 185 - all the stuff I've used is more like abs in that it doesn't soften till you get close to it's actual melting point.

So if you're car temp regularly hits 100c - then you might have problems. But then I suspect you'll have similiar problems with any kind of plastic.

Like I said the material chemists have been working overtime on material characteristics. And I don't honestly think that any of the pla on sale now has the weaknesses of pla a couple of years ago. Could be wrong, but I can only go on what I've printed and how it behaves.