Underbody skirts are proving the best way for 53-ft trailers to meet the EPA's SmartWay certification program and the new California Air Resources Board (CARB) requirements. These Transtex side skirts by ATDynamics can provide fuel efficiency gains of up to 7.4% at 62 mph, which with low rolling resistance tires is almost enough for SmartWay certification. Aluminum wheels also add SmartWay points because of weight reduction, and PSI inflation system for tire protection. The refrigeration unit must meet a different regulation regarding release of particulates. This Great Dane Super Seal trailer is equipped with Carrier Transicold's new Vector 6500 hybrid diesel-electric unit that was introduced at the Mid-America Trucking Show.