Is There Somebody Who Can Tell How To Make A Homemade Gas Saving Device?

There is no bolt on product that you can buy or build that will improve the efficiency of your engine. What you can do is keep your air filter clean, regularly maintain your car, and possibly change your driving style.
I know of no gas saving devices on the market that actually work, if there were car manufacturers would have used them at some point. They are mostly fraudulent claims that take advantage of people who don’t have a large technical understanding of engines. This is supported by the EPA !
The EPA performs tests on these systems. Here is a list. None of them work, many of them reduce efficiency or can cause harm to your engine!http://www.epa.gov/otaq/consumer/reports…
I can tell you right know, car manufacturers have already maximized the efficiency of their car engines for that specific car. The engine engineering teams CELEBRATE when they gain a 0.1% increase in efficiency! Engines are carefully designed to operate in certain conditions. Drastically changing these will reduce your efficiency or cause harm to your engine.

Jack up you giant SUV and drive a honda beneath it.

Make your car run on vegetable oil. It’s awesome! Check out the links. Good luck!

the bus