I’m always amazed at the things people will believe. Today I got trackback spam from a “water for gas” site on my miles per gallon post. (The trackback has since been deleted.)

I hadn’t run across this particular “technology” yet, so I dug into it a bit. It turns out there are dozens of sites out there claiming you can add a water-based fuel system to your car to significantly improve your gas mileage.

The gist of what they’re claiming is simple:

1. You use energy from your car’s electrical system to electrolyze water into Hydrogen and Oxygen.
2. You then run the gaseous hydrogen and oxygen back into your intake manifold where it burns in your engine’s combustion chamber, resulting in more power with less gasoline used.

Sound oh so simple. Except that this is yet another instance of someone peddling a perpetual motion machine.

Here’s the problem: The first law of thermodynamics states:

The increase in the internal energy of a system is equal to the amount of energy added by heating the system, minus the amount lost as a result of the work done by the system on its surroundings

In layman’s terms, this means you can’t get something for nothing. Applying that to the water for gas system, it basically means you will use more energy electrolyzing the water into hydrogen and oxygen than you will get combining them back together when you burn them in your engine.

In other words, if you took the gasoline completely out of the equation, you would eventually have your battery die because the engine wouldn’t make as much energy as it produced. (See this breakdown of the math if you want more info.)

What is more interesting than the bunk science displayed here is the willingness of people to be duped by this and respond with things like “but my friend has one and it works great”. Here we have some guy in middle-America (with little or no scientific or engineering experience and certainly without any of the proper equipment necessary to actually test this) telling you that the last 200 years of science and engineering are false and that perpetual motion (or snake oil) are real. The fact is, most of these scams are actually MLMs and Pyramid Schemes, do I guess we shouldn’t be surprised at the misleading information.

Remember people: If something seems too good to be true, it almost always is! The ultimate test for this in on, however. Bruce Simpson has offered up a million dollars to the first person who can prove it works. Read more over at the One Million Dollar HHO Challenge site. (He’s got a bunch of other great links to the real science involved here in case you want more info.)

So thanks to the trackback guy for letting me learn a bit about this new form of Snake Oil. Hopefully this will help a few more people save their money for things that actually will save money on fuel, like cars that get better mileage.

This week my MakeZine newsletter had an interesting article in it that referenced a post called Miles per Gallon vs. Gallons per Mile.

Suppose you had a household with two cars, and each car needs to be driven 10,000 miles per year. One car consumes 34 MPG, and the other car consumes 18 MPG. Since gas is expensive, you want to replace one car. Because of utility constraints, you have two choices:

Replace the 34 MPG car with a 50 MPG car — a 16 MPG improvement

Replace the 18 MPG car with a 28 MPG car — a 10 MPG improvement

Which car replacement would save you the most gas?

Of course this is one of those tricky math tricks that your average American gets totally wrong because the curve on this kind of think is non-linear.

After a nice analysis in the blog post, bunnie confirms the unexpected:

When you run the numbers, replacing the 34 MPG car with a 50 MPG (a 16 MPG improvement) car saves you 94.1 gallons per 10,000 miles, whereas replacing the 18 MPG car with a 28 MPG (a 10 MPG improvement) car saves you 198.4 gallons per 10,000 miles — more than double the savings.

Or, to give an even more clear-cut example, replacing a 5,000 MPG car with a 10,000 MPG car saves you just one gallon of gas, whereas replacing a 1 MPG car with a 2 MPG car saves you 5,000 gallons of gas, using a fixed mileage of 10,000 miles driven for comparison.

Read the entire post for all the info. Nice work bunnie!