Do they materially help with bugs on the windshield.

 

most dont. they used to be bigger and deflect more wind. now they are small and streamlined

 

Agreed.

They do a great job of keeping the paint on the front of the hood from getting rock chips though....

 

Only if the bugs fly at the same altitude as the deflector.

 

I have read posts where those who have put bug shields on their trucks state that they suffered mpg vs driving without the shield. If you are concerned about rock chips in the paint near the grill you may want to consider a AVS Aeroskin. It lays flat on the truck so it doesn't block the wind anymore than the truck does without it and protects the paint that it covers.

 

No, but do keep rocks off the leading edge of the hood.

 

Short answer: No. Some of them do look good though.

 

I have found that they only cause a change is airflow such that the wipers do not function with the same efficiency at highway speed.

 

It's mainly to prevent rocks from hitting the hood...

We call them hood deflectors here. I don't even know why they call it bug deflectors.

 

Initially I didn't think so, but I've noticed when I drive to visit my daughter in VA my bumper and grill are plastered with bugs and my windshield has very little. So maybe it is deflecting some critters.

It definitely does protect the hood from chips and looks pretty cool IMO.