Devices that claim to improve gas mileage

I keep seeing these on eBay, and there seem to two common varieties. One is a fan sort of thing that’s supposed to act like a turbocharger and force more air into the combustion chamber.

The other is a magnetic device that goes around the fuel line, which does something to keep fuel molecules from “clumping.”

Are these the automotive equivalent of colon cleansers?

Yes, but instead, they remove 20lbs of unburned fuel from your fuel lines…

Alas, as much as we wish some of these things actually worked, it’s all snake oil.

The Mythbusters tested a handful of mileage-boosting products in episode 53.

If someone’s trying to tell you that such things really work and are amazing and the greatest invention since sliced bread and such, ask them this: “So if this miracle mileage booster is so great, why wouldn’t the auto manufacturers buy the patents and put them in every car they make, since they’d be able to claim higher mileage and sell more cars?”

The answer, of course, is that auto engineers know that it’s all horseshit. The “Tornado Miracle Fuel Saver” is exactly as effective as putting a chunk of cardboard in your air intake, except that the cardboard would cost a whole lot less than $70. ZMax Miracle Lubricant is tinted mineral oil. Magnets have no effect whatsoever on gasoline.

If you want better mileage, maintain proper tire pressure. It’ll have a more dramatic effect than any aftermarket snake oil.


As Smokey Yunick once said, there are only so many BTUs in a gallon of gas. While American automotive manufacturers seemed resistant to innovate in the 1970s, most companies will make use of anything available that would improve their cars’ fuel efficiency or emissions.

Nitpick: On a carbureted car, a cardboard spacer could insulate the carb from the higher engine temps, cooling the fuel in the bowls and cooling the incoming air a little. This could cause the engine to be more efficient at full throttle since the denser intake charge would mean more air/fuel by weight enters the engine.

A friend of mine asked me about these things a while ago. I said, “if they worked, you’d see racks full of them for sale at every gas station.”

Interestingly, Warren Brown, WaPo’s automotive writer, wrote on Sunday about a fuel-economy enhancer that he saw, and tested, to whit: a fuel vaporizer that pre-heats the gasoline. He claimed the it worked as far as he could tell, increasing the test cars mileage by 50%. Going in he had the same opinion: that if such a thing worked, it would be snapped up by the oil companies, so his only thought as to why it hasn’t is that the major automakers aren’t willing to assume the liability risk of installing such a a device.

You can read the original article here(free registation required)

Many, many years ago I discovered the JC Whitney catalog. I found a miracle fuel saving device. I pointed it out to my father and suggested that he buy one for the family car.
His response was a classic. He thumbed though the pages, showing me all the different gas saving devices “This one saves 20%, here is one that saves 25%, here is another that saves 12%, why if we buy them all we can save 147% of the gas we buy. We will have to stop and pump the tank out every few days.” He then went on to explain the concept of snake oil and there is no such thing as a free lunch.
I miss my dad.

I’m not sure that gas stations would sell them if they worked- they are in the business of selling gas, after all.

Well some devices do work. I put a cold air intake, new muffler and a hard bed cover on my truck and I improved my gas milage 12% from 16 mpg to 18. Most of it is bunk but there is stuff you can do.

I’ve heard that adding acetone to gasoline (not gasoline-ethonal blends) does increase MPG, might be a bit harsh on the fuel system, but not that bad. The cost of acetone however makes this pretty much a break even deal, but (if it works) it would increase the range that you could drive before filling up.

Another down side is that you want to make sure you don’t get any on the paint while trying to pour it in the gas tank.

Dremel tool or Sawzall!
Just cut out a bunch of body panels and needless parts.

I think we’ve done this discussion before.
Doesn’t seem to help at all, even aside from the cost of acetone.
And based on your past posts, kanicbird, I suspect my patented BrickUnderThrottle device is just what you need to add 15-20% to your gas mileage…

The money back guarantees are the draw, but they don’t have to refund the money, since it’s pretty hard to prove they received it and harder to prove they didn’t pretend to mail a refund. And since they don’t care about their reputation to get customers (word of mouth would all be negative), refunds are the last thing on their to-do-list. It takes hundred of complaints to get a stern letter from whoever in government gets those letters, and they have like a couple of years after that before they have to go out of business and start a new scam.

Totally uncalled for

It would be, if it was in the nature of a personal attack and if you minded being accused of driving fast.
I honestly don’t know you well enough to bother with personal attacks, nor do I engage in personal attacks on this board.
I have no problem with you and doubt that either of us is genuinely upset over being accused of a lead foot.
I was using it as a setup for the Brick Under Foot joke.

That article is a load of unmitigated crap, FTR. This guy rode along in a demo vehicle, did not have any test equipment, he did no inspections, demonstrated no real technical knowledge, etc. Who the hell is he? Is he even an Engineer, or just the typical “automotive writer” who happens to be the only journalist on the staff who can figure out how to pop the hood on his car? His test was to ride with the guy until the car died? And that’s all? Holy dogshit, I should throw my Engineering degrees in the trash and start selling Una’s Patented Olde Tyme Bacon-riffic Gas Saver (the secret ingredient is…no, can’t say…) Because apparently, it wouldn’t take much to get written up in the Washington Post.

As I’ve, and others, have posted before - the first question to ask is “why?” As in, if they claim that overcoming combustion “inefficiency” is responsible for this 50% increase, you have to ask - does that mean that 33% of your current tailpipe emissions are unburned gasoline? Or improperly burned gasoline? Not very likely - check out Federal standards on the allowable CO and unburned hydrocarbons, and you’ll see it’s a minuscule fraction of the total gasoline that goes in.

So…where does the “combustion efficiency improvement” come from? Where is the magical extra 50% in energy?

I don’t imagine that their money back guarantees have any gimmicks, aside from the fact that you pay $19.99 plus $9.99 s&h (for $3.00 in shipping charges), of which the latter is non-refundable. These things they sell on TV aren’t generally sold by the manufacturer, but by a marketer. All they want is the s&h fees, and don’t give a crap whether they have to make a refund.

To add to Una’s excellent post, speaking from a car guys perspective 45 MPG really isn’t that impressive. First off Florida is as flat as flat can be. No gas wasted climbing hills. Secondly they drove a steady 65 MPH. Nice round speed. No jack rabbit starts, no hard acceleration, some wind resistance, but not nearly what you would get at say 75-80. We also do not know the exact volume of gas in the “cell”. It could have been holding more than 1.0000 Gal.

To give you a comparison my 2005 Volvo V70 will deliver 34-35 mpg at a steady 70 MPH. Needless to say my Volvo is a heavy battle cruiser compared to a '90s vintage 626.
Color me underwhelmed.