One big item often overlooked is to avoid ethanol! Use of E85 will lower gas mileage about 30%! If your car gets 30 MPG on pure gasoline (which is what the EPA mileage ratings are based on), it will drop to about 21 MPG when using E85. Plus it takes almost as much energy to process ethanol as you get back from it. Also, this energy comes from petoleum-huge amounts of natural gas and Diesel fuel are consumed in the process.