First of all thank you for your feedback!
I agree - this is a great idea, but there is one thing.
In this case each city/department will have to upload its own unique "wrap", which will entail an increase in the load on server disk storage and might affect players. Usually, developers are against this. That's why I made a uniform design for each of the vehicles to reduce the load on the server and storage. So basically u just change a color to a city PD.
In any case, your idea is worthwhile. I will think about how to improve the design or make it more unique.
By the way, you'll probably like the design I done months ago
https://imgur.com/a/NA0CoqM