cartechboy writes: How many Nissan Leafs does it take to power an office building? The answer, it turns out, is six. Nissan is the latest Japanese automaker to explore electric "vehicle-to-building" setups, this time with impressive results. The company started testing its latest system at the Nissan Advanced Technology Center in Atsugi City, Japan, during the summer. It found that just six Leafs plugged in to the building's power supply allowed it to cut peak-hour electricity use by 2 percent. Annualized, that's a savings of half a million yen (about $4,800 US) in electricity costs. How it works: The building pulls electricity from the plugged-in vehicles during peak-use hours, when power is most expensive, and then sends the power back to recharge the cars when grid prices fall. Nissan says the system is set up to ensure the cars are fully charged by the end of the workday. (Is this a devious secret way to make sure workers stay until a certain time?) Next up: Why not just do this using batteries--never mind the cars?