So far i've found out the Turismo is the big earner (cuz you cannot get many infernuses around, and they're not worth the hassle since they do not pay out as much as the turismo), for each turismo you turn in to stevie's garage you'll get 11000$, and its an easy exploit to get the "Half Million" Achivement/Trophy, just go to Grotti (car dealer round-the-corner from the algonquin penthouse) and jack one, losing the cops is easy once you get to the bridges, just be careful to get it pristine to the garage, cuz any slight scratch or bump will, and i mean *WILL* cost ya big time :P hope this helps, add me if you want to play on xbox live, tag: Der Feniks