Drive-Z serves can be hit from either side of the service box and to either side of the court. It is not recommended to hit this serve from the center of the service box as the ball will often bounce right toward where you are standing.
Here's a video example of the Drive-Z from the left side of the service box. This serve is designed to attack a right handed player's backhand, or a left handed player's forehand.
And here's the Drive-Z from the right side of the service box, aimed for the back right corner. It's a great serve to lefties, and as a way to mix up your serve to righties.