A saver mountable whose economy is unverifiable

This gadget Mount promised and wonder but it must be to do battle with reality. This saver mountable appears to be a miraculous product and a minimum investment for maximum return and what to leave pensive skeptical especially because it is extremely difficult to see any improvement in the economy or driving and although I use every day then are what the economy is substantial or infinitesimal is the whole mystery.
When you know that most types of magnets economisateurs not even have been approved technologically fuel saving term and costs several hundred dollars eyes closed should we trust a product that costs 10 euros. So to choose the case or the scam of the century.