Soon after Californians started queuing up in gas lines in late April, advertising executives began laying out new marketing strategies. Suddenly, products from frozen chicken to automobiles promised fuel savings and quick relief from the energy crunch.

Atlantic Richfield Co., which is based in Los Angeles, developed a campaign to try to get across the message that there would be no quick fix for the nation's energy problem and that the country needed to pull together and use its available resources.

But Arco executives changed their minds. They decided that, with oil companies held in such small esteem by the public, and with political electioneering about to get under way, a preachy advertising theme would be "a very tough sell," as one Arco ad man put it.

In its place, the Arco public relations people developed a consumer-oriented campaign dubbed "the drive for conversation," geared toward instructing drivers how to obtain better gas mileage.

The elaborate campaign received a test run here two weeks ago, and will be unveiled here officially today.

Four Arco caravans -- each one composed of two cars equipped with special gauges, a portable dynamometer, audio-visual equipment, reams of literature and crews of from four to six persons -- will crisscross the country setting up displays in shopping centers, county fairs and government centers.

Although there will be complementary fuel-efficiency driving education programs for government workers and high school students, the focus of the campaign and its most costly component will be displays at which members of the public will be invited to "drive" a car mounted on a dynamometer, while an audience looks on and hears about gas-saving tips.

At the La Cumbre Plaza shopping center in Santa Barbara, volunteers put a gas-guzzling GM Malibu Classic through its paces twice each -- following directions of a modulated voice over a loudspeaker inside the car. The before-and-after experiment measured gas consumption and demonstrated that good driving habits require less gasoline.

For the first seven minutes, a tape recording instructed the driver to make jackrabbit starts and abrupt stops which, if the car were actually moving, would cause severe distress in even the heartiest of stomachs.

The second part of the experiment was an exercise in "mellow-drive." The speed of the car was reduced and the driver coasted, gently touching the accelerator, softly working the brakes.

All the while, a master of ceremonies told the small audience that what was being demonstrated was "common sense . . . the light use of the accelerator . . . anyone can do it."

The scene resembled a game show, and Mark Freemon, the emcee, tried out a new line. "I'd like to take this time to say that speed kills mileage, and speed also kills yourself," he said.

At the conclusion of the second phase of the test, the emcee announced a 24 percent savings in gas consumption during the second run -- not too startling a result.

Arco executives estimated that the $2.3 million campaign will consume about 40,000 gallons of gasoline during its 15-month run, but they hope that the savings through education will more than make up for it.

The tips offered are common-sense suggestions: Avoid short trips. Keep your car tuned. Minimize constant braking and rapid acceleration.

However, according to Arco, engineers have concluded that less-obvious suggestions also may conserve fuel. They advise reaching optimum cruising speed as quickly as possible without "drag racing" starts, and they also have determined that a car operating with an air conditioner running and the windows rolled up uses less gas than one operating with the windows down because it has to overcome less wind resistance.

William E. Duke, manager of Arco's national programs, said the oil company's "drive for conservation" is based on research conducted by the U.S. Department of Energy and the transportation department of the Douglas Aircraft Co.

Visitors to the Arco display here were handed packages containing plastic-coated stickers, a cardboard slide rule to calculate miles per gallon, a poster, brochures and a plastic key ring.