Honda is turning its 2009 Insight hybrid cars into acceleration nannies. This new Ecological Drive Assist System (EDAS) features a chameleon-like speedometer, turning from green to blue if you're driving too rambunctiously. It's all in the name of saving the planet, encouraging drivers to ease off the throttle with an easily-seen color code.
Push the Econ Mode button, and the helpful monitoring begins. The system also issues you an electronic report card, showing you how wasteful you've been and offering suggestions for further fuel savings. Honda's EDAS idea is like an uglier version of Ford's sexy SmartGauge going into its 2010 Ford hybrids (if the company still exists by then). Both these designs are marginally useful; all that shaming would probably get annoying after a while.
Aside from having an econo-nag in the car watching your every move, I like this idea of a color-coded speedometer. If you could pre-set speeds for it to depict in a rainbow of colors, that might be a good way to keep your eyes on the road, using peripheral vision to get speed cues. As a volunteer instructor for a brand new driver, I can tell you this would be particularly useful for beginners.