I saw a huge semi truck regurgitating exhaust fumes in huge quantities through the exhaust pipe. That's when I got an idea. What if there was a car that ran on gas fumes and/or other types of vapors? The car would still pollute the air, but it would consume more fumes to run than it would release so the input is greater than output. This could slow down pollution of the air greatly and dramatically. There could also be a device that gathers fumes and vapors while driving, therefore being able to go miles and miles without stopping. I did some research on this, and it turns out that I was not the first person to have this idea.