Hello. I have a great suggestion that I think would be a small, but great detailed addition. I notice in a lot of older cars that are not well managed, that they all have fogged headlights, or windshields. Currently beats look unrealistic due to the glass, and headlights being spotless.
My old Dodge Caravan had a bad case of the foggy headlights, all you would need to do to get it in-game would be making a new texture for the headlight glass (I think)
just make a new texture for the headlamps and glass in photoshop/paint.net, the devs could easily do it, its just not high on the priority list right now, if you want to make it just for yourself it would be a very easy process
It's quite easy to add this to the game yourself, as it only requires modification of a .dds file if you don't always want it to be foggy but have it as an option, you can make the .dds a new entry for Livery.
I've done this a few times. Like the others said, it is just a matter of editing materials and a few (or just one in some cases) .dds files. For making them faded, it'd just be a matter of creating a slightly-yellow layer over the original .dds and lowering the opacity. As an example, this is what mine looked like after I added a tan layer over the original dds. (keep in mind the brake light glow textures have also been edited) and to the same effect, you can blacken lights too:
