The study cited a couple posts above was from when DST was extended into early March and to the first week of November. It doesn't cover the winter.
Yes, that study only analyzed the extended DST. But just think, during the winter people need heat and light right? Maximizing the amount of time the sun can provide these two necessities while Americans are awake during the winter should help reduce energy costs. Anybody who disagrees with this would have to argue one of these 3 points.
1. Permanent DST doesn't maximize Americans waking hours of daylight during the winter.
2. The sun doesn't provide natural heat and light.
3. Americans don't turn down their thermostats or tun off the lights when they go to bed.
Perhaps with more waking hours of light in the evening, people will go out more during the winter and there would be an increase in fuel consumption. But the business community probably won't mind if people are out and about an hour longer during the winter spending their money at shops and restaurants. What a horrible thing.