There is no licensing that needs to be negotiated with regards to aftermarket upgrades on cars in the real world, none! You buy the car, you own the car, you do what you want with the car, the car manufacturer can say or do naff all.
In a video game this is entirely different, and every little item needs to be discussed and agreed upon. And anything to do with the cars themselves, including the after market mods available in game for that car, are set by the manufacturer. Not T10, not aftermarket body kits, not even Microsoft themselves. That is how licensing works for a video game that uses real cars.
This is why I said this in my last post:
I have bolded the most important lines to read