Jian ... thanks for being the physics wizard on this ... I was gonna do this but didn't know the formulas.
The Chip they give you just make you burn more gas. I would buy one of these for testing with their return policy if they shipped it to me from a 10 block radius of my home.
All of the scams that have been out there usually have a dead givaway. They always say the same thing .... Increased HP/Performance and Increased MPG. There is no way that this can happen ... in order to get more HP out of an engine you have to give it more fuel ... period. The formula is here in the text about the highest HP production car in the world ... which is a VW at heart:
http://auto.howstuffworks.com/bugatti.htm
"1,000 horsepower is equivalent to roughly 2.6 billion joules per hour. A gallon (3.8 liters) of gasoline contains 132 million joules, so a 1,000-hp engine has to be able to burn just over 20 gallons of gasoline per hour.
However, car engines are only about one-quarter efficient -- three quarters of the gasoline's energy escapes as heat rather than as power to the wheels. So the engine actually has to be able to burn at least 80 gallons per hour, or 1.33 gallons (5 liters) per minute."