Bug shields and fuel milage

Recently my local newspaper ran a story about a trucking company that removed the bugshields from their trucks. They claim to have saved almost 0.5 MPG. Is this possible? If so, how much would fuel milage increase if I removed the bug shield from my Dodge Ram?

Why don’t you try it and find out, and report back here.

I’m not sure there is a “bug shield MPG” equation out there…like lprocter said, you’d have to calculate your current MPG, take off the shield and do the same calculation again and there’s your answer.

There is no way of knowing without doing it. Frankly it is possible your mileage will go down, but not as likely. Chances are the difference will be small in any case.

The problem is airodynamics is a complex subject. While there are general rules (which would say you should gain some mileage removing it) the only way of being sure is wind tunnel test or real life test.

Removing a bug shield from a tractor trailer for a modest gain is one thing…removing from a car or light truck is something else.

The bug shield probably does decrease your gas mileage…and maybe you’ll get .5% better gas mileage!!! Calculate that out to see what the savings is over the life of the truck. Then you have to ask…is the bug shield really working??? If it is then compare that to how much you think keeping the front of your vehicle clean is worth to you.

I think your forum handle answers that.

There is no way fuel economy improved by 0.5 MPG on those trucks solely due to the removal of the bug shield. That’s an improvement on the order of 5%.

It seems high to me also, but I can’t offer any real proof.

Thanks to all for your replys. (Except for roadrunner) I used to own a small trucking company. To me it seems like a bit too much of a savings. Also their test was a rather small test. With the large number of different styles of vehicles and shields it would probably vary between vehicles.
The problem with me running a test is that my vehicle is driven infrequently, with mulitple drivers over different types of terrain and in differing weather. I am going to be taking it to Mississippi later this year and a 0.5 MPG savings would only save me 5-6 gallons for the trip. So MikeInNH, you are right that there are other considerations.

Hey, that was just Roadrunner’s rapier wit coming out!

Heh heh, he doesn’t know me.

FWIW Daydreamer, I drove big rigs for better than 12 years before becoming a crane operator and after keeping track of mileage both before the bug whacker was mounted and after, there was no noticeable decrease in mpg.

No two trips down the road are EXACTLY the same which makes calculating a difference practically impossible.

Ok, Sorry if I jumped to conclusions. The company was Watsontown Trucking company in central PA. They are claiming over $500,000 in fuel savings. However they seem to have only performed two trips for their test. One with and one without the bugshield. It was on a dedicated run with weather that was comparable. I am currently in the medical field so to extrapolate that kind of savings from just two trips seems extreme. A well designed study should have several dozen trips at least. Just thought the concept was interesting.

You will save depending on the size of the bug shield. If you have the one that doesn’t protrude far above the hood, you will save nothing by removing it. If you have one that reduces your airflow through your dash vents, get rid of it immediately. I had a big one on a Mazda B 2000 and I had to run the blower on full speed to get any air at all.

There’s no way removing a bug deflector alone from a tractor trailer saved .5 mpg. Tractor trailers get between 4 and 7 mpg and it depends on what they are hauling, how heavy it is, the terrain, the distance hauled, quality of the fuel being burned, the way the driver handles the truck, condition of the trailer it’s hooked to, and a host of variables. With all the other more pertinent variables primarily weight and terrain I don’t see any way possible a bug deflector makes much more than a scant difference in mileage. A .5 mpg gain on a rig is large.


Having worked as a company truck driver, I often wished my truck had a bug shield. I think you should keep it. It creates a pocket of air between the bug shield and the windshield that really just shifts the impact of air from the windshield to the bug shield. Your overall aerodynamic profile doesn’t change that much. I tried to demonstrate this in the figures below. In either case, the air must impact a flat surface, which for all purposes makes the difference in fuel economy a wash.

Keeping your windshield free of bugs so you can see is wise and the slight price you pay in fuel economy is small enough to be worth it.