An acrylic hood protector disrupts the smooth flow of air over your car. Does this help or hinder fuel economy at highway speeds? The Subaru Crosstrek XV has a tiny rectangular bit at the rear of its roof rails that wind tunnel tests have shown to improve highway fuel efficiency by 1 mpg. So small details count. Disrupting smooth airflow at the rear of a car can reduce suction/drag and improve efficiency at highway speeds. But what about the rest of the car? An aerodynamics engineer would be the best source for this. But has anyone done a controlled experiment with and without a rigid hood protector? If it hurts fuel economy, there are film protectors that can be used to prevent stone chips. If it helps fuel economy, I'll leave mine where it is.