I've noticed that the mirror covers in my 06 xA's sun visors have slots that look like they're about the size of business cards or credit cards. (See image.) I've always been curious to know what those slots are for or why they're there. Do any of you know?

 

not sure official purpose...i always thought maybe insurance card? ive just always hated the warning images printed on the visors

 

close the mirror cover and those indentions create a pocket on outside of mirror cover to stick registration/insurance ID. I use it for that

 

https://en.driveplaza.com/expressways/toll.html

It's a Japanese car designed for driving in Japan, thus the convenient holder for the expressway toll card/pass. You get the pass ticket

entering the toll section, then show it when exiting the toll section to pay.