9.23 A typical fully-loaded highway transport truck has a weight of 350 kN, a frontal area of 11.5 m2, and a drag coefficient of 0.8. Using drag reduction devices such as a cab top deflector, chassis side skirts, and vortex generators to reduce the wake lowers the drag coefficient to 0.65. Estimate the power requirements for a truck driving 100 km/

hr with and without drag reduction devices. The coefficient of rolling friction for the tires is 0.01.