I also seen your other thread here. You use NVE, NVE overrides the vanilla vehicles with enhanced versions, to my knowledge, you cannot replace the vanilla police models using a normal patchday, as NVE will just overwrite them. I personally use addon vehicles that have their own dlcpack, and that correctly works to overwrite NVE. With that, presumably, you can create your own dlcpack and add whatever models you want into it, to then overwrite NVE's. (Make sure to have the correct DLC metadata)