One day, when I was about 10 (so this was the late '80's), we were in science class and the 'speriment of the day was dropping the 9V battery in water and watching the bubbles form.
What are the bubbles? Well, hydrogen and oxygen via electrolytic breakdown of chemical bonds.
So I started formulating ideas for how to pipe those highly ignitable gasses into an air intake on my moms 'Vette.
That's, Chevette.
And I figured I'd need some alternating plates in water, and an alternator or 7 to provide the juice.