Hello guys.
I think that im pretty experienced with modding. 
There is a thing i just can't figure out though.
Like i want a a lot of different cars that i can choose between, and not the regulary as Buffalo and all these main gta police vehicles.

There is just 1 problem, every car i try to download is police2?
And then that is the only one i can change, and then i have 1 car that i can play with...
It's really annoying, yes i could just download a new one every time im playing, but that is not fun, i wanna change cars while im playing, but it's difficult when i dont like these main police vehicles..

You are aware you can just rename the file, right?

I tried that but it didn't show the car..

Then you probably replaced the files from a different vehicles.rpf than the one the game uses for that specific vehicle. For some reason Rockstar made it so the game pulls the stuff for one vehicle from a different file than those for another. Sadly, I don't know which vehicle should be replaced where, so I can't help you on that.

Use vehicle.rpf inside:

- x64e for police

-dlcpacks/patchday3ng for police2, sheriff, sheriff2

-dlcpacks/patchday4ng for police3

I think these are the only cars I've replaced, I don't know about the rest of them. But you should always read the ReadMe file that comes with the mod, it will always say exactly where you have to replace the vehicle. If you change the name to something else, find another mod that replaces the car you want and read its ReadMe to see which is the right location.

Yeah i figured it out, i have some awesome cars now!
Thanks man :P