Until you forget to plug it in one night. How is plugging in every night a waste of money? Whats the costs difference whether you not plug in for a few days and charge up one night, or plug in every night and maintain? You are still putting the same amount of charge into the car for those days. There is nothing wrong going days without plugging in, but one of the benefits of having an electric car is the ease of having a "full tank" when you get into your car every morning. Of course this is if you have a charge option at home. Keep in mind, if you want to precondition before you leave, it is better to be plugged in as well.