[TimAustinW]

You can keep doing missions with Brucie or you can get the auto theft jobs through him via the website and eventually you'll get it. Also on the big island in the the central area theres a upper crust clothing store that sells suits, can't remember the name of it, there's an exotic car show room next door. You can break the window with a brick or shoot it out. Not totally sure if the Comet (Cayman) is in there or not. But as soon as you're driving around in an expensive car you'll start seeing more on the roads. Then you can just jack one on the street.