DETROIT, D.C. SERIOUS; ABOUT CAR STANDARDS.

As mileposts go, last week's car-emissions announcement by Transportation Secretary Ray LaHood and Environmental Protection Agency administrator Lisa Jackson was an impressive one:

It set the federal government's first greenhouse-gas standard, and it also will lead to the biggest-yet boost in gasoline mileage.

Not right away, claro; decrees like this, even when they have Detroit's blessings, take many years to accomplish. For example, the 35 miles per gallon Corporate Average Fuel Economy touted by Jackson and LaHood won't be reached until 2016, and even then there are fudge factors that could render that amount imaginary; same for reductions in carbon dioxide from motor vehicles to 250 grams per mile.

Still, that would be better than the 2020 timeline passed by Congress two years ago.

The new clean-air and fuel-efficiency resolve are among the results of the Barack Obama administration's auto-industry bailout and the government takeover of General Motors.

And New Mexico had a hand in the process: When Environment Secretary Ron Curry adopted California's higher efficiency standards, and he and Attorney General Gary King joined California in its lawsuit against the Bush administration's EPA, Golden State Gov. Arnold Schwarzenegger's case gained momentum. By now there are 15 or so states seeking to impose their own standards -- and they represent a lot of buyers, even in today's tight times.

Therein lies some of the rub against the new federal announcement: Automakers will earn extra "carbon credits" against other pollution by sending their cleanest, highest-mileage cars to the leading-edge states. But the auto industry, reading the handwriting on the wall, was already planning to build cars to California-New Mexico standards -- and of course the whole country would soon be getting higher-efficiency cars. So some environmentalists are grumbling about the credits, but they ought to be glad for what progress they're seeing.

Jackson notes that the new rules include progressive improvements that would reduce oil consumption by about 1.8 billion barrels between 2012 and 2016. They also would reduce greenhouse-gas emissions by the equivalent of 42 million cars. For good measure, they might save car buyers a few thousand dollars on what they pay at the pumps, with or without a new round of price-gouging.

Purists in quest of fresh air also quibble over slack being cut to car companies that get serious about electric and hybrid gas-electric vehicles. But again, this beats Detroit's decades-old resistance to anything but big-engined behemoths.

Meanwhile, a lawsuit by the National Automobile Dealers Association still challenges New Mexico's standards. Perhaps the manufacturers' assent to national levels will lay that case to rest.

By next spring, expect further developments on the emissions and efficiency front. But so far, so good for a still-new administration.