Gasoline. Diesel. Bio-diesel. Ethanol. E10. E85. Compressed air. Hydrogen fuel cell. Switchgrass. Miscanthus. Reclaimed cooking oil. Plug-in electricity. Lithium-ion batteries. Which of the above will not be the preferred source of fueling our RVs in a decade? If you said gasoline, you are right. At least in its present, unadulterated form. Already some states (CA,