Look a little further into fuel cells and you'll realize that those are a long way from feasible on a mass scale. It'll be a few years before we see those, at least. Although I have ridden in a fuel cell powered chevy equinox. Drove nice. Sounded weird, all the cooling fans and whatnot for all the electrical stuff. Very complicated, but seemed near-transparent to the user. Probably a $150,000 car though. I guess they built a handful as a test fleet, sorta like that honda or toyota fuel cell car that the media actually hypes.
Gregg is right though, the efficiency gains for an internal combustion engine aren't going to come from better tolerances and such. The efficiency of the combustion, the actual conversion of the fuel to energy, needs to be increased, and less of the energy needs to be lost to things like heat in the exhaust. There is room for improvement there with head design and such, but the kind of improvements cited in the article just aren't likely. We've seen major improvements over the years, though. Compare the efficiency of a 4.6L or 5.4L ford motor with the old 5.0 and 351. Compare the efficiency of an LS1 to an LT1. Major improvements, but nowhere near what's cited in the article. And that's with the resources of some of the largest companies in the world driving the developement with teams of hundreds of engineers.