As part of a useful and informative feature on U.S. oil supply and North Dakota’s Bakken Formation boom of shale oil, Popular Mechanics crunched the numbers to test political claims that we can achieve ‘energy independence’ by 2020.

Before we even get to the details, the piece makes an important point, albeit implicit rather than explicit. Discussions of ‘energy independence’ are in fact a proxy for oil independence. Among all the major sources of energy, the only one we must import is oil. That makes oil—and not ‘energy’ at large—the root of our national dependence.

Popular Mechanics makes clear that, contrary to political claims on both sides, independence by 2020 is impossible to achieve with the current fuel mix, even if Canadian tar sands are included as a domestic source. The math on the Bakken so far has shown a more than 10-to-1 ratio of increase in number of wells to increase in output (+280% wells for a measly-by-comparison 25% production increase). That inefficient ratio will be tough to sustain. And the necessary Gulf of Mexico contribution is even less likely.

Yet even if these unlikely supply scenarios unfold, we won’t be oil independent. The numbers show that even if electric vehicles constitute 45% of new car sales (wouldn’t that be nice?) as the most optimistic estimates imagine, and automakers sell 1.5 million natural gas vehicles by 2020, we wouldn’t get there.

There are a couple important takeaways from this exercise. First, meeting the improbable production levels for the pricey oil from Bakken and the Gulf of Mexico would mean sustained high oil prices. Can we afford that? The larger point is that we cannot achieve oil independence within the current fuel and technology mix. We need to open the market to promote competition and spur innovation that can diversify our fuel choices, fatten our wallets, reduce our national debt, and create jobs, not to mention give us cleaner air and fewer oil spills.