Something that works.
If you love your Wii, you'll love the Fuel Mizer, because they're based on the same technology of sensitive, small accelerometers. And they're equally easy to use. Just how handy are these awesome accelerometers? You can use the Wii to get fit, or the Fuel Mizer to get some serious fuel efficiency kung fu.
How much does driving style matter? It all depends on the driver. I recall a woman who called Click and Clack who was sure something was wrong with her car because her husband got 10 mpg less than she did. This can be a really, really big deal for some of the most aggressive drivers on the one hand, and it also helped an experienced driver . This accelerometer just sits there on your dash and shows pretty lights to tell you if you are accelerating or braking too fast. After a while you train yourself - after a while you take the thing out because you've changed your habits. It doesn't hook up to anything - and runs for a long time on the battery. Finally, a product that WILL save you gas, is not a scam and has some nice science behind it.