[doviatt]

You have summed up the entire contents of the corral in one post. That is impressive in itself.
I was more interested in data on things that did work to help support your end goal.
You are here with a pile of things that didn't work. You are asking for one, any one thing that you can package up and sale for profit. One simple device that every one can use on any car that guarantees efficiency no matter how inefficiently you drive. This thing you seek doesn't exist. There are a lot of smart people here (not including myself) that have experience, knowledge, science. Why discount their words, input and advice?