Someone recently forwarded me a “technical report” that claims that it is possible to run automobiles on water — with this miraculous build-it-yourself gadget that converts water into hydrogen and oxygen, then converts it to fuel that you use in addition to gasoline. (It was being distributed by email to break the conspiracy that keeps us all from using water to run our cars!)
As much as I would love to believe that such a thing is possible, I know better. Of course, that’s because I’ve seen this sort of idiocy before. Back in the 1970s, when I was young, the equivalent claim was that there were 200-mile-per-gallon carburetors that had been suppressed by the automobile companies, at the insistence of the oil companies.
The first part of the claim was absurd. A number of studies over the years concluded that no more than 40% of the chemical energy contained in gasoline was being converted by the internal combustion engine into motion. Why only 40%? Because any chemical process is inefficient — and especially a chemical process as clumsy as exploding gasoline vapor. Once you have converted that chemical energy into rotation, you lose some of it because of friction in the driveline, wind resistance against the body of the car, and flexing of the tires. There was room for improvement — but there was simply no way that a 4,000-pound automobile (as was typical in the 1970s) was going to get 200 miles per gallon. Even a 100% efficient system (which is not possible) wasn’t going to do much better than 30 miles per gallon with such a large vehicle.
The second part of the claim was even more absurd. If you ran a car company and you had the option of selling a car that consumed vastly less gasoline than its competitors, why would you not sell it and gobble up the market? Volkswagen, back then, sold a car that was a bit better on gas mileage than many of the American barges of the period, and it sold rather nicely because of it. Imagine if you could have bought a 1973 Impala sedan that gave you 200 miles per gallon? How, exactly, would the oil companies have prevented GM from selling it?