Although alcohol and automobiles do not usually mix, Sen. Birch Bayh (D-Ind.) waved a bottle of vodka around on the Capitol steps yesterday to show he is not afraid of mixing them - as long as it is in the gas tank.

Bayh then joined Albert Turner of Selma, Ala., in pouring vodka into the gas tank of Turner's roaring 40-year-old John Deere tractor to show, the senator said, that alcohol fuel may be an answer to the nation's energy crisis.

Bayh and several other members of Congress appeared at a Capitol rally of about 100 farmers, local officials and others, including singer James Brown, who want to encourage the use of alcohol made from either grain, wood or coal for automobile fuel. The legislators announced several proposals to do that, shouting over the chugging tractor.

Beside the tractor stood a sleek maroon 1965 Ferrari, also burning vodka, and 15 more assorted old and new cars, trucks and campers. They all were driven, trouble-free, from as faraway as Montana, Alabama and New York on mixtures of 10 per cent alcohol and 90 per cent gasoline.

"The age of cheap petroleum fuel is dead," said Pat Torgenson of Lambert, Mant, who helped organize yesterday's demonstration, "and today the age of a cheap, renewable resource fuel has been born."

Alcohol fuel's backers say it gives better mileage and produces fewer pollutants than gasoline; can be made from anything that grows, as well as from cow manure and garbage; and can go right into anybody's gas tank as an octane booster at 10 per cent concentrations, call "gasohol," without any engine adjustments.

"The American people don't take kindly to conservation efforts," Sen. Jacob Javits (R-N.Y.) told the crowd on the Capitol steps, "What they're find of is more production. That puts alcohol in the forefront of energy areas."

Alcohol's opponents say it is too expensive, puts out only half to two-thirds the power of gasoline, corrodes fuel tanks, causes vapor lock and would require such vast amounts of grain as to denude the farmlands.

"What's wrong with this program is that it's too simple," one speaker told the cheering proalcohol group. "In three days anybody can make a batch . . .common people can make their own fuel."

Sen. Charles H. Percy (R-I11.) called gasohol legislation "motherhood provisions" that all sides could support. "We've got to move it forward in the Senate . . ."

The Senate Finance Committee voted last week to exempt gasoline-alcohol blends from the four cent per gallon federal excise tax on ordinary gasoline. The measure comes to the Senate floor next week.

Other pending bills would set up an experimental fleet of alcohol-powered federal vehicles, provide fast amortization of alcohol distilleries and allow farmers to grow grains for fuel on land that is now set aside to avoid farm surpluses.

A bill sponsored by Reps. Dan Glickman (D-Kans.) and Rick Nolan (D-Minn.) would require most large gas stations to sell some alcohol blended fuels within three years.

In the Senate, 28 signatures were collected last week on a letter urging Agriculture Secretary Bob S. Bergland and Energy Secretary James R. Schlesinger to come up with "a comprehensive new effort" to evaluate renewable resource fuel possibilities. The signers included most of the senators who are influential on energy matters, including energy committee chief Henry Jackson (D-Wash.).

The organizer of yesterday's rally, independent energy consultant Richard Merritt of Bethesda, said in an interview that "big oil doesn't like alcohol because they have no control over it." Merritt said he sees himself as sort of a Ralph Nader of energy: "The only thing wrong with Nader is that he doesn't like cars. I like cars. America likes cars. Nader took on Detroit; I'm taking on Houston." Houston is a major oil company center.

The American Petroleum Institute, which speaks for much of the industry, has issued studies highly critical of gasohol. A study for Sen. Javits by the Library of Congress Congressional Research Service however, called alcohol fuels "potentially useful automotive fuels" and said technical problems are "readily solvable."