[byte312]

Yes, I understand that testing it is not easy. People don't like it either because we tend to go on faith and personal pride. We do it on the cheap because we are the little guys without the resources of the big 3 and Japan. What is DOT? Even if you can prove it to yourself, which always comes first, it is difficult to convince it to everyone else. I am not certain that I want to.
The greatest peril is personal injury, then legal issues with the EPA.
I stepped in it big with HHO. I had to drop my experiments because of legal issues, safety concerns, and alegations that it is all a scam. I had worked hard and spent over $3000. developing a complete system. I can live with looking foolish but, When you try out a modification on a car that violates the EPA rules and ignores federal safety standards you can have reason for concern. The fines are huge. Then you can worry about testing for mileage.
I am working on an electric car now. Here again, there are legal requirements, safety and the other issues. I will try to register the car and insure it as an electric car. After it is legal and safe, I still don't know if I can impress anyone with the mileage and performance.
This last point is only an issue because I think we all take pride in our creations and want to see other people follow our lead. We have tight budgets so we cut corners and leave most of the testing and proof to Myth Busters. I wonder how many illegal conversions and modifications are on the street. Maybe it is wise to build for ourselves and not advertise. I don't want to join a long list of others who attracted some very bad attention to themselves by selling thier creations or by talking too loudly.