Thursday, September 29, 2022


RV Mods: Fuel-saving devices for your RV?

By Russ and Tiña De Maris

If you recall that infamous scene from “Blazing Saddles,” you know that there’s a lot of gas floating around these days. Some of the hottest air in the marketplace is on equipment and additives “guaranteed to help you save at the gas pump.”

Add-on devices to modify your motorhome or tow vehicle come from a variety of directions. Over the years, we’ve tried several. There’s the “stick this in your intake,” and the device will somehow change the air flow, dramatically increasing the burn efficiency. Another: Add a little water! A small reservoir of water is placed under the hood and plumbed into the intakes. The water is atomized, and hey, presto! This “‘steam” expands in your cylinders, giving you more boost. Then there were (and, of course, still are) magnet assemblies placed over your fuel line. The story here is that fuel molecules are clustered and the magnetic field breaks up the clusters, resulting in better burn efficiency.

It’s like “snake oil” for your vehicle. How much will really save you money?

The answer is “not much.” Be skeptical of the following kinds of advertising claims:

“This gas-saving product improves fuel economy by 20 percent.” Claims usually tout savings ranging from 12 to 25 percent. However, the Environmental Protection Agency (EPA) has evaluated or tested more than 100 alleged gas-saving devices and has not found any product that significantly improves gas mileage. In fact, some “gas-saving” products may damage a vehicle’s engine or cause substantial increases in exhaust emissions.

“After installing your product on my car, I got an extra four miles per gallon.” Many ads feature glowing testimonials by satisfied customers. Yet, few consumers have the ability or the equipment to test for precise changes in gas mileage after installing a gas-saving product. Many variables affect fuel consumption, including traffic, road and weather conditions and the car’s condition. For example, one consumer sent a letter to a company praising its “gas-saving” product. At the time the product was installed, however, the consumer also had received a complete engine tune-up – a fact not mentioned in the letter. The entire increase in gas mileage attributed to the “gas-saving” product may well have been the result of the tune-up alone. But from the ad, other consumers could not have known.

“This gas-saving device is approved by the Federal government.” No government agency endorses gas-saving products for cars. The most that can be claimed in advertising is that the EPA has reached certain conclusions about possible gas savings by testing the product or by evaluating the manufacturer’s own test data. If the seller claims that its product has been evaluated by the EPA, ask for a copy of the EPA report, or check for information. In some instances, false claims of EPA testing or approval have been made.

To date, nobody has been able to invent a truly “free lunch.” In fact, publisher Popular Science took these and many other “fuel-saving devices” and put them to the test – using laboratory equipment to do scientific tests to find out the real truth about enhanced claims. In all cases, there were no increases in fuel economy, and in some, add-on devices actually decreased fuel efficiency. Check out their findings here.

If you really want to save money on fuel, skip the “add-on” fuel-saving devices. One of the best fuel-saving devices you can buy is a good, reliable tire pressure gauge. Use it regularly and keep your tires at recommended levels and you truly will save fuel. How much? Uncle Sam’s fuel economy whizzes say, “You can improve your gas mileage by 0.6% on average – up to 3% in some cases – by keeping your tires inflated to the proper pressure. Under-inflated tires can lower gas mileage by about 0.2% for every 1 psi drop in the average pressure of all tires.”



Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments
4 years ago

What about Diesel fuel additives, I often find big differences in power from one tank full to another, assumably from poor quality diesel. I have sometimes seen a 1 mpg difference using some sort of diesel treat, I also use it to keep injectors clean. And the truck starts better in very low temperatures.
I am driving a 2001 Dodge Ram Turbo, 3/4 ton

4 years ago

Going to talk about the “air tabs” ad on RV Times? If they really worked as claimed then every LD Trucker in the country would have them, so far I have only seen one truck with them on

4 years ago

Regarding the AirTabs:

There are claims of better handling and a cleaner backside that are harder to quantify, but the question of mileage has been pretty well reported…

The manufacturer claims to expect a 4% mileage increase across tractor trailers, RVs, and anything else they can stick them to. This includes liberal usage of the tabs on the tow vehicle as well as all over the trailer (not just rear edge). For RVs, 4% would typically mean 10.4mpg up from 10mpg…

Informal RV user surveys average to 0.2mpg improvement (2% at 10mpg), which is actually more effect than I expected.

Now let’s run the RoI numbers. Assuming tabs cost $250, gas costs $2.50/gallon, and you get 10mph before adding the tabs… you’ll save half to 1 cent per mile. So, the Return on Investment (break even point) occurs as soon as… 25,000 miles, more likely 50,000 miles. So, consider your own driving habits, and invest accordingly. My own rig already handles fine, and is unlikely to make another 50K miles.

4 years ago

Seems all rv’s are very thirsty,my Ford V10 Triton is a pig,it is what it is,Mr E.Musk made electic tractor trailors,this will be in rv industry in very near future,only than will it be cheaper travel costs,that being said you will pay dearly for this technology.

Gene Bjerke
4 years ago

A very good, low-priced device for increasing fuel mileage is a small balloon. Inflate it with helium and attach it to your right foot.

Lee Ensminger
4 years ago

I installed the AirTabs on my 2013 Koala 24 RBK. What I can tell you about MY experience [and only mine] is with the only change being the Air Tabs [same trailer, same tow vehicle] my 2006 GMC 1500 went from an average of 11 MPG to 12.5 MPG. I also notice a considerable difference in the sway induced by passing semi trucks. These are my experiences-as always, your mileage may vary.

Wolfe Rose
4 years ago

The only fuel saving device that WORKS is placing a thumbtack in your right shoe. Properly installed, you’ll be much kinder to the gas pedal.

I wrote an article on how I can sometimes briefly DOUBLE gas mileage (18,000lbs at 16mpg) and sustain adding 5mpg, if folks are interested.

Butch Brooker
4 years ago

I have the tabs on my motorhome, 37 ft. diesel and found reduced buffeting while behind semi’s but no increase in mileage. I did improve mileage by reducing my speed from 65 to under 60 by about 10 to 15 per-cent.

4 years ago

I’ve never seen those air tabs on any Semi passing me by. So if the truckers aren’t using them, and they drive hundred of miles every day for a living, how effective could they be?

4 years ago
Reply to  Larry

I put those on my 5er 6 months ago & am disappointed with the results. 34 ft fifth wheel pulled by an F450 diesel. I’ve driven 4M miles since then & have noticed zero difference in fuel mileage. I still average 8.5mpg, the same as before, with no changes in driving pattern or habits. Their other claim is a cleaner back wall of the rv with very little, if any, dirt being sucked around against the back. I’ve noticed a marginal difference on the back wall, but still a lot of dirt. I also put them across the top rear of the truck cab to quiet the turbulence in the truck bed to no avail. Overall disappointing expenditure of $230.

Lee Ensminger
4 years ago
Reply to  Fred

Fred, I’d be interested to know how fast you drive, since you don’t see any appreciable benefit. Indeed, I have a smaller trailer, pulled by a less-hefty truck, but I’ve gone from an average of 11 MPG to 12.5 MPG and am enjoying better handling regarding the push-pull influence of passing trucks. I use cruise control almost exclusively, and drive 55 mph, occasionally 60 MPH. After over 4,500 miles, I have tracked fuel consumption 1.5 MPG more since I installed the AirTabs. And I keep records of EVERY tank of fuel. Were you careful to follow the separation and proximity to the rear instructions?

Tommy Molnar
4 years ago

Also, staying put longer, which doesn’t really affect fuel mileage, DOES affect how much money you have to put out for fuel.

Like John Snell, I’ve wondered about those Air Tabs too.

John Snell
4 years ago

I’ve never believed any claims by these companies. There been out there for decade’s. But they do advertise in this rv publication ,about add on plastic pieces for your pull behind. I’m assuming they reduce drag on the unit.
Any thoughts on these?

4 years ago
Reply to  John Snell

See my comment under Larry’s post.

Wolfe Rose
4 years ago
Reply to  Fred

The theory of the airtabs is more about managing turbulence to break the vacuum behind squareback RVs. Aerodynamically, they are too small to have much effect, and most testimonials I would dismiss as wishful comfirmation bias (Lost $250? Of course you say they work). The creation of a rolling vortex would be too custom-tuned to be a 1-size solution.

The size that could have an effect is the spring-launched vanes you see on some tractor trailer boxes. BIG size difference.

Sign up for the RVtravel Newsletter

Your information will *never* be shared or sold to a 3rd party.

Subscribe to our newsletter

Every Saturday and Sunday morning. Serving RVers for more than 20 years.