As you can imagine, fuel efficiency is a hot topic here at PumpTalk. We're always looking for new tips to pass on to our readers about how to get the most out of their gas. In my relentless pursuit of gas saving tips, I came across a "fuel-saving" idea this morning that I hadn't heard before. The tip was that if you drive around with a half-tank of gas or less, you could increase your fuel efficiency. On paper, it makes sense. Gas does add weight to your car - and reducing weight in your car can increase fuel efficiency. But, as it turns out, consistently driving around with not much gas in your tank is not the best way to save on fuel.