How much extra gasoline would Americans use if daytime running lights were mandatory?

As gas prices spike daily, we're all looking to save money at the pumps. But if your car uses daytime running lights, be prepared to dig deep into your wallet.

When gasoline prices climb, people will do just about anything to improve their car's fuel consumption. Articles touting the top 10 ways to improve fuel efficiency pop up daily on Web sites and in news publications. For example, methods… » Full Story on HowStuffWorks