Increase MPG

Bottom line.....There is no magic. If there was, mfg's would do it. Truth is that most engines, today, are tuned to gve the most power for the least amount of fuel. It takes so much energy to move so many lbs. to a given speed. It takes x amount of energy to move so many square feet of area through the air. These are facts. A gallon of gasoline contains x amount of energy. If one trys to run the engine leaner, the valves and pistons overheat. Proof of this happened years ago when a certain mfg. decided that a computer could make and engine run leaner. The "lean burn technology destroyed countless numbers of engines, before the mfg decided to scrap the program.
The best way to improve mpg is sitting directly behind the steering wheel. It does more to improve or decline mpg than any bolt on device by a large margin.