The trucks are constructed from ABS plastic, a lightweight and rugged material that reduces the weight of these vehicles by around 1,000 pounds, compared to the usual sheet metal. Trucks of this size typically weigh around five tons, depending on the packages being delivered. The plastic body has a few other benefits as well. Painted sheet metal is both heavy (the paint alone can weigh about 100 pounds!) and fragile--a slight dent or nick makes the metal beneath the paint visible, at which point UPS has to service the truck to keep it looking fresh. But this plastic is brown all the way through, so it can suffer dents without looking mangled.