I was visiting home in the weekend, spending most of my time trying to get my internet-connection to work. As I was driving back, I noticed something. When I got to a downhill, I instinctively tried to accomplish zero gas expenditure. I released the pedal, and at halfway, the expenditure meter showed zero. I played a little fanfare and shouted “Perfect expenditure achieved!” in my mind. Why weren’t I given positive feedback, I wonder?
Imagine a car radio. It plays a nice soundtrack of whatever type of music you like. The on-board computer is linked to the gas expenditure meter, and as you drive forth, the music changes according to how much gas the engine eats and how fast you are going. The program checks how far you deviate from the average gas expenditure for the speed you are going. If you use more gas than is necessary, the music gains threatening tones. If you use less, like when you do not step on the gas on a downhill, the music speeds up and gains more tempo.
I imagine a system like this would get people to drive more economically. Sound is an efficient feedback system, as it does not require the driver to look at anything. Car manufacturers, take note.