Do window vents and rain guards on vehicles lower the mpg?

An open window alters a vehicle's aerodynamics in such a way that fast-moving air is drawn inside the car. Wind deflectors block this change by redirecting air into an arc pattern that flows around the sides of the vehicle. read more

Discussion in 'Gen 2 Prius Main Forum' started by JW87, Aug 6, 2012. read more

Side Window Deflectors are custom fit, in-window-channel, rain and debris guards that allow fresh air to enter and leave the vehicle while having the window still cracked during harsh climates. Side Window Deflectors also help reduce wind noise and allow interior heat to escape. read more