The Colorado Air Pollution Control Commission is asking motorists here to abandon their cars one day each week to help clear the air in this smog-bound Rocky Mountain capital.

The call for a voluntary "no-drive" day is contained in a commission-drafted air cleanup plan that will be presented this week to the Environmental Protection Agency under provisions of the federal Clean Air Act.

Privately, commission members admit the measure probably won't succeed in reducing pollutant levels to federal standards. But they say its failure might make it politically feasibel later to launch a mandatory nodrive program to reduce vehicle traffic, which is responsbile for almost 90 percent of the pollution in the Denver metropolitan area.

As Colorado and other states prepare cleanup plans for submission to EPA, atuomobile trade goups are launching an attack on clean air programs that increasingly point toward vehicle restrictions. The National Automobile Dealers Association is taking out full-page ads, including one in last week's issue of Time magazine, urging the public to "Help us protect your freedom to drive."

In Denver, environmentalists and health authorities are virtually unanimous in saying the Colorado plan doesn't do enough to reduce automotive pollution. Aside from its call for the voluntary no-drive day, the plan mainly endorese pollution-fighting measures already in the works. These include expanding local bus service, the federal motor vehicle emissions control program, and a compulsory vehicle inspection and maintenance program to begin here in 1980, long after some other polluted areas have started theirs.

"The whole timetable needs to be shortened," complains Diane Huling, president of the Denve Clean Air Coalition, a nonprofit group of antipollution activists. "There are a lot of people in the metro area who can't afford to wait for clean air -- seniors and the very young and people with chronic respiratory diseases."

Denver is noted for its majestic view of the Rockies, but on many days it could well be Cleveland for all that can be seen of the mountains.

Home of the National Asthma Center and onetime haven for respiratory patients because of its healthy air, this sprawling metropolitan region of nearly 1.5 million now sometimes ties with Los Angeles in levels of carbon monoxide, ozone, nitrogendioxide and particulate emissions.

Air quality is made worse by the thin air at Denver's mile-high altitude; by weather conditions -- wintertime temperature inversions that trap carbon dioxide and strong summer sunlight that helps create ozone -- by sprawl, the lack of good mass transit, and what some call Denver's love affair with the automobile.

Bue environmentalists have claimed citizens are more willing to get out of their cars toclean up the air than politicians give them credit for. In a recent telephone survey conducted by a Denver TV station, 67 percent of respondents supported a mandatory nodrive day for area motorists. That finding is "really interesting in view of the fact everybody claimed nobody is willing to do anything," Hulling says.

"As far as we're concerned, the politicla leadership is misreading the public," she says. "People are willing to do something, provided they're asked." Political leaders have seemed reluctant to find out how much citizens are wiling to do, environmentalists claim, and even more reluctant to do anything that could curtail an economic boom in the region.

Colorado's conservative, Republican-dominated state legislature failed this year to enact an air pollution control bill. It passed one measure, later vetoed by Democratic Gov. Richard Lamm, that would have stripped the power of the Air Pollution Control Commission, the state's designated air quality planning agency.

In what Colorado's assistant attorney general, Hubert Farbes, term "an absolutely reprehensible arrangement," an interim legislative committee, meeting between sessions, recently endorsed an air pollution bill written by a Denver law firm that works for a consortium of the state's major industries. The bill, Farbes says, would weaken the state's ability to crack down on polluting industries.