If you find yourself in traffic behind one of those big brown trucks from UPS, chances are you're not in a left-turn lane. As Mental Floss explains, the company has figured out that left turns wind up wasting a lot of time and gas as drivers sit there waiting for traffic to clear. As a result, many drivers' routes are comprised of a series of right-hand turns; the company says the policy has saved 100 million gallons of gas in the last decade. Backing up is frowned upon, too. Click for the full article, which has 17 other "secrets" of the company fleet. (More UPS stories.)