these things must have a device on them that tricks the gas gauge into thinking there's more fuel in the tank than there really is. that's the only thing i can come up with as to where their numbers come from.
and beefstew, the reason i agree with makg is because he obviously knows his shit. like he's said a million times in this thread alone, it's basic laws of science. you can't go outside those parameters. (not tryin' to kiss ass or anything) he, unlike YOU or any others on here who have been scammed, actually gave us simple comprehensible explanations on why it doesn't work and never will in it's current incarnation. you just tell us you do this and this and this and tada! presto! 10 more mpg's. i hear what you are saying, it just doesn't compute. sorry.