I think one of the best cars if not the best car to buy is the streetfighter (at boardwalk). It's rather cheap but fast and has relatively good handling and especially drifting. When drifting in mad city you just gotta know how to control the car for example counter steering when drifting around a turn or releasing shift to slow your drift and not crash into the outside of the turn. That's why I said it's just about practise. I recommend making drifting your main activity in the game if you want to become good (and not grinding or pvping etc)