We all remember the blue beta police cars in GTA 3, they are meant to be in Vice City too. This is uncovered by the game files itself. I found out there was an UNUSED colour in the game which is called: POLICE CAR BLUE. I reactivated it for all police vehicles.
Installation is "easy as can be": Just replace the file in the data folder with the one from my archive.
PS: If you like this mod, check out my other mods.