Ignorant people always are proposing dumb mandates for the auto industry. What's harder to accept are foolish demands coming from sources with access to the best information.

In his recent State of the Union speech, President Bush said, “Let us build on the work we've done, and reduce gasoline usage in the United States by 20% in the next 10 years.”

There is no way we can reduce gasoline use that much. We’d have to shoo every V-8 engine off the highway, tax gasoline until it hit $8 a gallon; set a national 45 mph (72 km) speed limit and eliminate half of all drivers.

There are 250 million motor vehicles in this country, and that number goes up about 4 million units a year as new vehicles hit the road and old ones are scrapped.

We used 142 billion gallons (538 billion L) of gasoline last year, and that goes up an average 1.5% a year.

Even if all the dreams come true and General Motors builds its fantasy plug-in hybrid-electric vehicle in five years; diesels become a major factor in the marketplace; hybrid-electric vehicle sales soar; and hydrogen cars became practical; they still will account for a small fraction of the 300 million vehicles predicted to be on U.S. roads in 10 years.

It will be a miracle if we can hold our fuel use steady, let alone achieve a 20% reduction.

The president also said to reach this goal, we must increase the supply of alternative fuels by requiring 35 billion gallons (132 billion L) of renewable and alternative fuels be produced by 2017, nearly five times the current target.

We’re really talking ethanol here. In the U.S., we get ethanol from corn. In 2006, ethanol production consumed nearly 20% of the corn crop.

Increasing production that much will raise the price of cattle feed so high, no one will be able to afford a steak. Surging ethanol production already has caused the price of corn to double in just two years and is the highest in a decade.

The hope is to make ethanol from offal such as switch grass, whatever that is. But right now we can't do it, and it's reasonable to figure the corn lobby will fight any substitute.

Plus, we can't import ethanol from Brazil because of high tariffs designed to protect domestic farmers.

But it's not just the president who should know better.

Senator and presidential hopeful Barack Obama is advocating a new corporate average fuel economy standard that’s sure to finish off Detroit and all the auto suppliers in his home district of Illinois.

What's good about the president's proposals, and the talk in the new Democratic Congress, is it shows our government leaders are thinking about energy.

The great American engine of innovation is revving up. Three cheers. But let's not set goals with failure built in.

Jerry Flint is a columnist for, and former senior editor of, Forbes magazine.