Just tried this for a bit, fun as hell. I got a helicopter from the harbor by the city, and then got it stolen from me pretty quickly. Also, is there a way to kick people out of passenger seats or something? I was in the passenger seat of a helicopter once, and then I just inexplicably fell out of it.
The greatest moment though, was in the city, I got a sports car, and was driving on the right side of the highway. I was going pretty damn fast, and all of a sudden, there was this other car in my lane coming head on! We couldn't see each other in time, so we crashed, both cars flipped over the guardrail and onto a nearby roof. Mine went on the ground, so I bailed out and went on the roof where the other car went. The other guy and I sat there laughing for a minute, we both got in his car, but the roof had guardrails, so we couldn't get it off that roof.
Also, what's this Lost Island everyone keeps talking about?