I recently used the add police 3 mod on lcpdfr from gtapolicemods, I found the file on sparkIV and I added my own car and skin, but when I boot the game up, I can't find the car...anyone know what's going on?

Its not a normal car....Use a spawner or a trainer to spawn it

Or if you have a scripthook installed (should come with lcpdfr), press the ~ key and type in "spawn police3".

I have scripthook installed, and when I type that it, it says cannot spawn that object...any idea why? also, police3 isn't in vehicles.img, its in newveh.img, is there a way to move it? or is it supposed to be there?

its supposed to be in newveh.img. Sometimes it takes a few tries to spawn, or sometimes you just need to download a trainer like Asuna said

If it says you can't spawn the model, it's probably because the model isn't in the game, or the game isn't being told to load the model.

Check default.dat, gta.dat, and images.txt.

C:Program FilesRockstar GamesGrand Theft Auto IVcommondata