Vehicle design has seen radical improvements thanks in large part to NASA aerodynamics and fluid dynamics research. As vehicles move down the road at highway speeds, they must ‘push’ the air in front of them out of the way. Large trucks in particular must move huge quantities of air, creating high pressure zones around the vehicle. The compressed air spills around the cab in swirling vortices. At the back end the opposite occurs – the air is unable to negotiate the abrupt turn at the end of the vehicle and creates a low pressure zone. These effects produce significant aerodynamic drag on the vehicle and decrease fuel efficiency. In the early 1970s, Edwin J. Saltzman, Dryden aerospace engineer, felt these turbulent effects first hand while cycling to work.