Bob Stoffel, Senior VP of UPS, revealed an unusual way to save time and money to Fortune:

Stop making left-hand turns.

Engineers map out every route, he says, and provide right-turn only directions to drivers.

This seemingly silly strategy has paid off: UPS's routing software shaved 20.4 million miles off their routes last year* while delivering 350,000 more packages. It also diminished CO2 emissions by 20,000 metric tons.

Don't believe it? MythBusters tried it out. The show had drivers take the same route, only some made right turns while others turned left. The results were similar.

Why does this work? A few reasons, says Stoffel. Turning right decreases safety hazards and delays. If a driver is stuck waiting for traffic to pass with a left blinker on, it's going to set them back. Jutting out into traffic is also a good way to get side-swiped, especially when driving a big truck.

*The 20.4 million figure is not just from making right-hand turns. It is the total miles the routing software helped UPS save last year in all capacities.

Stoffel explains the logic in the video below.