Pouring sugar into gas tanks used to be just a nasty practical joke. But now the people of Brazil are doing it as a matter of policy, and the laugh is on those not-so-jovial fellows from the oil-producing countries.

One of the men behind Brazil's revolutionary program to end its dependence on foreign oil is engineer Lamartine Navarro Jr., 48, who in 1975 built the first distillery capable of producing fuel alcohol from Brazil's plentiful sugarcane without making refined sugar first. His efforts were inspired by the 1973 oil shortage and avidly supported by the Brazilian government, which imports 80 percent of its petroleum products. In 1975, anticipating the OPEC price increases that contributed to its 110 percent inflation rate and huge trade deficit last year, Brazil began its "Proalcool" program to substitute alcohol for gasoline as an automobile fuel.

"No one believed in the program in the beginning, especially the auto industry," says Navarro, a civil engineering graduate of São Paulo's Mackenzie University. Now they do. The first alcohol-powered cars became available only last April, and for a while sales were slow. (Some Brazilians used the alcohol fuel pumps to make cachaça, a favorite national quaff.) But since the cutoff of Iraqi oil in September, business has been booming. Now about 300,000 of the nation's cars are running on 100 percent alcohol. Some are modified gas-fueled models (the changeover costs about $660). But one-third of all the 1981 cars in Brazil are alcohol-powered, and the target date for phasing out half of all gas-fueled automobiles is 1985.

At $1.67 a gallon—compared to $3.10 for gasoline—alcohol is cheap to the consumer in Brazil, even allowing for the fact that it gets about 18 percent fewer miles per gallon than gas. (Government taxes and import limits on oil account for the difference in price. Alcohol fuel actually costs $50 a barrel, as opposed to $36.50 for a barrel of OPEC oil.)

Lamartine was vice-president of a natural gas company in São Paulo before he became involved in alcohol production. The son of a Sao Paulo lawyer, he lives with wife Maria Cecilia and their three children in that city, where he has an engineering firm, and commutes to the capital city of Brasilia, where he serves as a trouble-shooter and jawboner for the Proalcool program. An avid pilot, Navarro has flown his own plane for the past 15 years; his current six-seater, which he uses to reach Amazon fishing spots, runs on conventional high-octane aviation fuel.

Alcohol's benefits for Brazil are unquestionable: It is a cheap, efficient, relatively clean, indigenous and renewable resource. But whether it could be a practical replacement for gasoline in U.S. cars is an open question. Department of Energy study groups have equivocated. But President Carter's energy plan for 1981 called for production of five billion gallons of gasohol—the 90 percent petroleum, 10 percent alcohol fuel—and several U.S. corporations are doing ambitious research into alcohol's potential. Many American farmers are already making alcohol from corn, grain, wood and even sugar beets to run their farm machinery—at a cost as low as 500 a gallon.

Navarro doubts the Brazilian solution would work here, but he is hardly an unbiased source. "The volumes of alcohol you'd need are tremendously high," he says. "You use so much gasoline, and if you made alcohol from your corn or grain, it would be expensive. You'd probably have to import it from Brazil instead." After a few more lumps from OPEC, a $50-a-barrel fuel could begin to look very sweet.