The big engine under the hood isn't built for sitting still. That's why truck owners are turning to auxiliary power units, or APUs, for a seamless source of energy when the truck isn't moving. Time: 8:42; size: 8 Mb. Includes an interview with Will Watson of Auxiliary Power Dynamics, maker of the Willis APU. Theme music is "Under a Sky" by Edie Carey. Exit music is "Spectre Swing" by This Spy Surfs.