The answer to the question posed in the first sentence, is a resounding yes! Stone and bug deflectors work by altering the actual aerodynamics of your vehicle. ... While the deflector won't be able to turn everything away from your hood and windshield, it will make sure that most debris won't even touch your vehicle.

How effective are bug deflectors?

The results showed that bug deflectors most likely reduce your fuel economy between 1-3% –but that's only when you're traveling at highway speeds.

Does a bug deflector reduce mpg?

According to their study, bug deflectors decrease fuel economy 1.5% (or so). That's not a heck of a lot of change. Another study of commercial trucks pegged the fuel economy decrease at about 3%. So the data suggests that the fuel economy impact of a bug deflector is minimal (1.5-3%).