But the new cars weren't the only focus. Organizers wanted to let people know how to make their old cars run cleaner too.
Micheal Bolten, California Consumer Affairs, says "On a day like this, with the air as bad as it is, absolutely. It really stresses the importance of people keeping cars well maintained and doing what's necessary to keep the air clean."
Some of their simple suggestions to save gas and prevent pollution include learning how to keep the right air pressure in your tires, and keeping your engine oil clean.