One of the main themes of the Chicago Auto Show -- and probably of a lot of auto shows nowadays -- is the effort by automakers to sell more fuel-efficient vehicles. More specifically, the challenge is not to produce them; it's to get consumers to buy them. The Big 3 already offer plenty. The big problem is convincing buyers that they represent a good deal. People just don't want them. They're either too small, too expensive, or too odd looking.

Over time, improved technology is likely to improve the overall picture. Batteries will get better. There will be easier availability of hydrogen for fuel cell vehicles. E-85 will be sold in more places. But what if that's not enough to get people to buy the cars that Washington wants on the road?

The simple answer is that automakers will refuse to sell them -- or they'll use price to ration them to the few willing to pay a premium. Come 2020, new fuel economy standards will require automakers to sell a fleet that meets a sales-weighted standard of 35 miles per gallon. So for every one car sold that gets 22 MPG, they better sell multiple cars that get 37 or 38. Ultimately, the best way for the manufacturers to do that is to raise the price of that 22 mpg car to make sure only a few can afford it. Maybe the profits from that Dodge Challenger will subsidize the sale of the latest hybrid. Or maybe Detroit will just bank the higher profit.

Without a significant improvement in the technology -- an improvement that is of course, entirely possible -- the car manufacturers will simply be in the position of denying the consumers what they want. They might even reap an inflated profit from doing so.