Really all you need to change is your hoses in the car, and even that is debateable
Buy ethanol too, that also helps with my profit sharing!
Corn is the here and now...there are many other biomass options coming down the research pipeline that will pretty much guarantee we won't be running gasoline much longer in our cars.
That said, we still need crude oil for lots and lots of things...plastics and chemical stock so while we'll reduce the dependence, it will still be there. AND...the one thing a lot of people don't realize, you need some sort of fuel to run ethanol plants. Be it natural gas, coal or fuel oil...
The debate is still out as well as to wether there is a net gain in the manufacture of ethanol. ie...does it take a gallon of oil to make a gallon of ethanol, including farming, transporting and manufacturing?
Most studies point to a small net gain but there are disputing testimonies