UPS drivers do not make left turns unless it is absolutely unavoidable. This is because, according to UPS, “left turns mean idling, which increases the time a route takes. Left turns mean going against traffic, which increases exposure to oncoming cars. Right turns are faster. Right turns save fuel.”
In fact, UPS has saved gallons of gas, effectively reduced its carbon emission, and saved millions annually by making sure UPS drivers avoid left turns as much as possible.