I don't remember the numbers on exact mileage,but I know of two designs that work.The best kept secrets are kept in plain view and made to seem rediculous.I've never bought any plans or worthless gizmos myself.And saying a 300 mpg car is impossible is ignorant.A hybrid electric car with a gas or diesel engine powering an onboard generator can be built from readily available parts and plans that can achieve in excess of 100mpg at 30% engine effiency.You don't need 100% or more effiency,which are both impossible,to build ultra effecient cars.I can only say I know of two designs that work giving around 70% effiency.Try to tell me it's impossible.Just like not that long ago it was impossible for a heating furnace to be more then 60 some % efficient,Right?Everyone knew it was impossible to get better efficiency from a furnace.And the people who claimed they could do better were nut cases.Huh.And all of a sudden 85% efficient furnaces or better were a reality.I'm not making outragous claims of anything at all impossible.Hey,don't most people KNOW you can't run a diesel on SVO and expect it to last?And as far as patent rights go.Before the patents ever run out the owner of the patent can copyright it and have all patent records removed from public access.Right?Go ahead and ridicule me for two designs that I know work.Then when they someday do surface,remember what I said.Every one used to know space travel was a great fantasy,but went against the laws of physics also.Perpetual motion machines are most likely impossible.But why is 70% fuel efficiency impossible?Why so closed minded?Traveling faster then the speed of sound was know to be impossible.Only a few years ago,almost everyone knew a non hybrid car could never be built that woud be practicle and get more then 90 mpg.Everyone knew that if it was possible,the car makers would jump at the chance to build them.Just like everyone knows it now right?So I guess the VW Lupo is just another urban legend also?Doesn't that cars engine already exceed those laws of physics about fuel to air ratio and effiency?