There are incredible energy saving user interface lessons to be gained from good hybrid car gas consumption displays. Driving my Honda Civic Hybrid becomes the ultimate energy game: saving money, beating personal records, and building upon previous accomplishments. A digital display reports lifetime mpg (48.8 for 100,000 miles in my case) while the bar graph reports current instantaneous consumption. It becomes an unconscious biofeedback process: when the bar retreats to the left (bad MPG), lift the gas pedal foot to reduce gas consumption. A functional display like that makes it possible to save energy without even thinking about it.