Obtaining the ‘68 firebird

So I just picked up this game about two weeks ago and still not sure the best way to get cars that aren’t just in the Autoshow. Now my dad likes to play a bit too, just hopping in cars and driving around the map. He has a ‘69 firebird in real life and I thought it would be cool if I surprised him with it so that he could drive his own car around in game but I’m having a hard time figuring out how to get the car. I’ve looked up YouTube videos but they seem to be out of date or maybe I just suck at follow directions, any advice is greatly appreciated