My own example (MAX, shown above) gets 100 mpg at 55 on the highway and cost me less than ten grand, which ain't bad for off-the-shelf technology. (Latest update April 11, 2013) photo by Royce McCornack, courtesy of Mother Earth News Here’s the scoop on making your own low budget high mileage sports car. Make Your Own MAX The plans and links and parts you need to build your own.