A combustion air intake apparatus for a truck, tractor, or bus vehicle for highway use includes an air deflecting element that is selectively deployable to cause dynamic air pressure created by vehicle motion to increase static air, pressure within the intake apparatus under appropriate conditions. Deployment or retraction of the air deflecting element is responsive to at least one of forward speed of the vehicle, air pressure downstream of an air inlet opening, or throttle position, and may further be responsive to detection of precipitation and/or particulate material. An air deflecting element may include a moveable plate or flap, moveable louvers, or a moveable duct.