Ethanol- made from corn and sugarcane.
Biodiesel - made from soybeans.
Nice thought, but what about all the water, land, and food that will be destroyed? And how will we be able to feed our demand?
Hybrid technology - uses gas and electricity.
They get around 40 miles per gallon, but their battery system has high energy needs and causes pollution - some poisonous.
Electric cars - run on electricity.
If you are travelling a short distance, under a hundred miles, they are good because they will reduce the nasty tailpipe emissions. Then you have to find a place to charge it and wait an hour or more for it to charge. The pollution from the power plants is a concern, but not a bad option.
Hydrogen - made from natural gas.
It takes a lot of energy to produce hydrogen, and the emissions are carbon monoxide. Not Good.
There are others, but whatever you decide, investigate it thouroughly before you make a major purchase.