EXCELLENT USED TRADE IN, SUPER CLEAN WITH WARRANTY REMAINING FROM PETERBILTDOUBLE BUNK SLEEPERThe Model 579's features are the direct result of our customers' input. We've considered the feedback of over 100 user tests and interviews with drivers, techs, and safety and maintenance managers in applications including over-the-road sleepers, LTL day cabs and vocational applications such as tankers and aggregate haulers. The results add up to many technological advancements and a distinctively styled, super comfortable, sleeker, more aerodynamically and fuel-efficient Model 579. One that endured million-mile endurance tests and extensive field validation. No wonder it's the most technologically advanced, fuel-efficient Peterbilt – ever.