Under-Carriage Plastic Protection Came Off; Could that Affect Gas Mileage?

I accidentally scraped the underneath front part of my Prius on a cement block at a parking lot; partially ripping off the plastic piece that covers the motor. I guess it's there to protect the motor from such scratches and dents. Anyway, I took the plastic piece off because it was dragging on the ground. Ever since then I've noticed that my gas mileage has been terrible. Down to 34 mpg instead of 42-45. Could there be any relation? Maybe the under-carriage cover helps the car's aerodynamics? Any thoughts would be appreciated.