With car skins selected by AI more suggestions come in mind
Skin suffix used as display name for AI cars
You could append skin suffix to car name so you can have unique car name for each skin so you can recognize them easily and add more diversity, this will work in race only and won't affect car selection or time trial records.
example: while AI takes "caror.bmp" skin for NY 54 its name could change into "NY 54 OR", now you know what is that green thing you never seen before.
Change skin selector
As is the skin selector is a bit bare: car name could apper on top of skin selection with default border having arrows on left and right. Skin suffix could eventually appear on this name aswell.
Random skins less random
A thing I've seen during random car races is that, being skin selection random, certain skins will appear more often than others (as example I had a rotor race with 12 red rotor and only 4 black). A system that will be randomly pick a skin excluding skins already picked would be cool (when every skin is picked the system resets, of course), in this way skin variety would be more balanced.
Let host decide every skin for clients on random sessions
An issue we discovered is that if we use random cars online skins are not syncronized. I think the skin selection system could be applied host side, it doesn't matter if clients doesn't have host skins installed.
Custom skins pushed from clients (?)
This want to be more a discussion than an actual suggestion: considering that car skins are usually small files would be possible to let clients push their skins to other during online races? this feature could be disabled client side and a file size limit could be applied.
Should -nouser disable custom skins?