The Reason UPS Drivers Always Leave Their Doors Open

UPS's boxy, brown trucks aren't the flashiest vehicles on the road, but they have a few quirks that attract interest from onlookers. If you've ever received a delivery from the company, you likely noticed that the passenger-side door on their trucks is always open. According to Grunge, this choice reflects UPS's commitment to efficiency.

Every second is valuable on a delivery route. Opening and closing a car door may take only a few seconds, but when drivers do this all day while making deliveries, those seconds add up. To save time—a.k.a. money—UPS instructs its delivery workers to keep their right-side doors open even when they're behind the wheel.

Though it may look like the trucks are missing a door altogether, the doors are actually built to slide to the side rather than swing open. That means drivers can close and lock the doors when necessary, but they rarely do this unless they're done for the day.

During long stretches of driving without stops, the opening can still provide some much-needed ventilation in hot weather. Because drivers are hopping in and out of the vehicles throughout the day, the trucks don't come with built-in air conditioning. This makes them more energy efficient, but it also means they turn into oversized microwaves during the summer. When the temperatures inside a UPS truck approach dangerous levels, keeping the door open is a lifeline.

Efficiency is the driving force behind many UPS quirks that seem strange to outside observers. You'll never see a UPS truck turn left, for instance, because driving against the flow of traffic wastes gas and time. Here are more industry secrets from UPS delivery workers.

[h/t Grunge]