Gmod Car Spwaner Gun and Car Dealer NPC

I was wondering if someone could help or make me a gun that spawns a car in front of you and a npc that lets u select a car buy it and then the gun spawns on the road. This is thru DarkRP.
Any help would be appreciated.

May I ask why in the world would you want a gun that spawns cars?

So police can spawn their police cars.

Why use a gun to spawn the car?

What else, not really a gun which u see just like what the pocket and keys r like.