MileMax located at getmilemax.com is a scam. The newly created website, which has no physical business address or telephone number, claims they have an OBD2 chip device, a fuel-saving gadget that helps you get more miles per gallon while improving your throttle. But, ask yourself, what is the name of the company that created this fuel saving device and where are they located? The answer, no one knows. So why enter your credit card information on a website you do not know who is operating and from where?
The Mile Max Fuel Saver

Email: official.milemax@gmail.com
Also, do not be tricked by the so-called reviews, they are fakes, being used to convince potential victims to buy the so-called fuel saver.
If you were tricked into buying MileMax, open a dispute with your bank to have your money refunded. And, you may need to change your credit card because you do not know whose hands that information is in and if it will be used fraudulently.
Websites like MileMax will taken down soon and will be replaced with a new one, selling the same product under a different name.