Used cars
For example, will all car buyers in the game be only buying new cars from your/ai companies or will we have to also compete with used car sales. If something like this will be part of the game it could be kind of cool to see how your cars sell after 5 or 10 years, and how much they depreciate compared to other brands. It would be a small part of the game of coarse but something like this could be used for company reputation points, I don't want to play a game where I'm running a used car lot. (wouldn't be surprised if they already made Used Car Lot Tycoon)
I didn't want to put this in the suggestion section, if it wasn't mentioned before/in the plans already than I don't see it as necessary by any means.