This car looks fine with that livery but livery looks little bad nice concept but change some colors and add more white look how LSPD vanilla cars is done i will help you if you need a hand.

@WeteranBF3 Ok thanks ^^

Right

The seal is far too big, it covers nearly the entire bottom part of the driverside door.
No department tends to have just the acronym for the department and nothing else on their cars, they nearly always spell out the entire department name.
The police text on the front is also slightly too big, it looks weird.

Cant speak for the rest because I cant see the roof or the rear because pictures of them aren't provided.