The Department of Transportation issued new fuel economy standards this morning for 2011 model year vehicles. According to the National Highway Traffic Safety Administration, the new restrictions will bring the combined car and light truck average to 27.3 miles per gallon, up from 25.3 miles per gallon for 2010 vehicles. The NHTSA estimates that the tighter standards will cut fuel usage by 887 million gallons and carbon dioxide emissions by 8.3 million metric tons.

That’s not quite the 1.4 billion gallons of gasoline we’d save by switching 2 million people to the new Prius, which gets 50 mpg. But now we’ll just have to buy 730,000 Priuses each year, instead of 2 million, if we want to reduce our dependence on OPEC oil by half in ten years.

Or we could just keep increasing incentives for fuel efficiency. Either way.

Analysts said Toyota’s downward revision, its second in two months, showed that the worst financial crisis since the Depression was threatening not just the Big Three but also even relatively healthy automakers in Japan, South Korea and Europe. Many other companies will also soon be reporting losses.

Worse, analysts said that they expected next year to be even more painful, amid forecasts that the global economy would continue to slide until at least the summer. This could cause a significant shakeout, driving smaller and weaker companies into the arms of a smaller number of bigger, richer players.

So for all that talk of “retooling factories” and “Chevy Volts” and “smaller, more fuel-efficient cars,” the message is clear: In this economy, folks aren’t buying any cars — not even Toyota Priuses — largely because they can’t access the credit to finance such a purchase.

The Bush bailout forces the Big Three to craft a plan to return the companies to profitability. Toyota’s news is indication that that task just got much tougher.

Why is that bad news for the Big Three? Because there’s been this line of argument that Ford, General Motors and Chrysler would be performing splendidly right now if only they’d focused more resources on the production of gas-sippers instead of gas-guzzlers. While there’s certainly truth in that criticism, Toyota’s announcement indicates that auto companies are suffering across the board, regardless of what models they’re able to produce. Indeed, Prius sales in November dropped more than 48 percent relative to the same month a year ago.

So even if GM were shooting its plug-in Volt off the assembly line like Pez, it still wouldn’t solve the company’s troubles because the credit crunch and lack of consumer confidence means no one’s buying anyways. That’s a tough message for supporters of the Detroit bailout, who’ve been arguing that the Big Three will be fine if they just get some help retooling their factories to make higher mileage cars.

As David Cole, chairman of the Center for Automotive Research, said just a few minutes ago in what’s probably an understatement, “All automakers are in big trouble right now.”