This sounds like some sort of ridiculous April Fools' joke, but turns out it's actually true - UPS delivery trucks rarely turn left in the US. The strategy was devised by engineers to increase efficiency and save on fuel. After significant research, they found that that one of the main causes of idle time resulted from drivers making left turns, essentially going against the flow of traffic.
Since then, UPS estimate they've managed to save 10 million gallons of gas, reducing their carbon emissions by 100,000 metric tons – the equivalent of 5,300 cars off the road for an entire year. TV programme Mythbusters even tested out the theory for themselves, and it genuinely works. Watch the clip below.