A group of researchers at MIT and Princeton University are testing to figure out how to best save fuel when stopping and re-starting cars at traffic lights, and they're using the iPhone to do so. The smartphone is mounted on the car's dashboard, and uses the camera and GPS information in a system called SignalGuru that tells the driver when it's best to slow the car down in order to save fuel (so you're not always revving up the engine and then having to put on the brakes when the next light pops up). The system works, apparently, and in Cambridge, MA testing, fuel consumption was cut down by 20 percent.
The system was also tested in Singapore, where most traffic lights change the length they're displayed based on the traffic around them. In that area, as opposed to the US (where lights are generally on fixed schedules), the prediction mechanism didn't work quite as well. It was off by up to two seconds, say the researchers.
It sounds like any indication can be helpful. It's hard to see if this is something that could eventually make its way to the consumer market -- more likely it would be used in commercial vehicles as a solution. But you never know -- if the system works on an iPhone and there's an in-car mount that's standardized enough to work at the right angles, your phone could be telling you when to slow down on the road, and saving you money at the same time.