Until about five years ago, Deere & Co. used oil-based products to manufacture the exterior panels on its John Deere agricultural combines. But then the company decided to start using alternatives, displacing some of that oil. The typical combine's panels now include material processed from about 21/2 bushels of soybeans and about half a bushel of corn.

"Here's a new use for corn and soybeans," said Barry Nelson, a spokesman for the Moline, Ill., company, "and we can put it right on the combine for our customers harvesting this crop."

For weeks now, economists have watched the steep rise in oil prices and concluded that a combination of improved energy efficiency and market competition have buffered the U.S. economy against the inflation and other economic problems triggered by earlier oil shocks. Since the first Arab oil embargo in 1973, American industry has shaved by about 50 percent the amount of oil it takes to produce $1 of economic output. During the latest oil spike, the fear of losing customers has led businesses to trim profits, squeeze other costs, or postpone investment and hiring instead of increasing prices to consumers.

So far.

From major manufacturers to local bus companies, evidence is building that the slack in the system is being used up and soon consumers will feel the effects of $50-a-barrel oil.

Whirlpool Corp., the home appliance maker, has announced plans to raise prices by an average of 5 to 10 percent on average, largely because of increases in its oil-related costs.

The price changes likely "would be reflected at the consumer level," and not just absorbed by retailers, Chairman Jeff M. Fettig told industry analysts recently, according to a transcript of his remarks prepared by CallStreet LLC.

Giant Food LLC, the Washington region's biggest grocery chain, has experienced a 30 percent increase in the cost of diesel fuel for its delivery trucks over the past year, and it has absorbed some of that through computer-aided loading and routing of the trucks to maximize efficiency, said Barry F. Scher, vice president of public affairs.

But, he said, eventually "all of our costs go into that can of peas. . . . I can't say they won't be passed on."

Capitol Trailways of Harrisburg, Pa., has so far limited increases in the cost of its regional bus service to a surcharge of $1 a ticket on some routes, but that is only because it benefited from a long-term fuel contract that is about to expire. When a new fuel contract is negotiated, "it's going to be tough," to determine how much of the increased cost to pass along, said the company's vice president, Skip Becker. Higher prices, he worried, could discourage ridership.

According to many economists, including those at the Federal Reserve, the rise in oil prices has shaved about $75 billion off the nation's economic growth so far this year and is continuing to restrain business and individual spending. However, the effect on prices, employment and consumer pocketbooks has been muted for a variety of reasons.

Energy costs now make up just 7 percent of all household expenditures, with gasoline accounting for less than half of that. Meanwhile consumer inflation overall has been relatively tame in recent months, though many economists forecast it to rise in the months ahead.

Even at more than $50 a barrel, oil is still cheaper after adjusting for inflation than it was when it peaked in 1981 at about $80 a barrel in today's dollars.

In addition to the increased efficiency of existing companies, economic growth has come increasingly from service sector firms that consume less energy than older industries, many of which have moved offshore.

San Francisco-based Levi Strauss & Co., which once operated dozens of U.S. apparel factories, closed its only remaining one last year and now describes itself as a design and marketing company.

The manufacturers that have remained and grown, and which account for about a fourth of the nation's total energy consumption, are themselves more fuel efficient.

The value of U.S. manufacturers' production grew by 45 percent from 1992 through 2003, after adjusting for inflation, said David M. Huether, chief economist of the National Association of Manufacturers. Yet the sector's energy use rose only slightly. As a result, by last year, manufacturers overall used 32 percent less energy per dollar of output, he said.

With oil accounting for a smaller portion of overall costs, it becomes easier for businesses to absorb temporary increases. This is particularly true for the many companies that have enjoyed strong profit growth over the last year.

This reduction in oil-dependence has been achieved through a variety of ways, including the increased use of oil alternatives.

Gannett Co., for example, publishes about 100 daily newspapers across the country, including USA Today, using soy-based color inks instead of the oil-based color inks it gave up roughly 10 years ago.

"It was environmentally a good decision," said Tara Connell, spokeswoman for the McLean company. "What we discovered after we made the change, I'm told, is we actually got better color."

Ford Motor Co. has shifted away from heating oil to natural gas as a power source for the boilers in its factories, said George Andraos, director of energy supply and efficiency. Ford, based in Dearborn, Mich., made the switch for environmental reasons, cost efficiency, improved reliability and safety, he said.

Since the late 1980s the diversified technology company 3M Co., based in St. Paul, Minn., has reduced the amount of oil-based solvents it uses to manufacture various tapes and other items, said Katherine E. Reed, a vice president for environmental health and safety.

However, many manufacturers, builders, transportation companies and other businesses say their profit margins are starting to be squeezed severely as they pay more for crude oil, diesel fuel and petroleum-based materials such as plastics, chemicals and asphalt.

Whirlpool, of Benton Harbor, Mich., said its costs rose by $60 million worldwide in the three months that ended in September, compared with the same period last year. They are expected to keep rising, by another $100 million in the last quarter of this year, compared with the final quarter of last year, because of higher materials and transportation costs. Some of the materials costs were for pricier metals, but the biggest change was in the cost of oil-based plastics, Fettig said.

Whirlpool's planned price increases are "unprecedented," both in size and scope, he said, adding that they are "appropriate" given "the magnitude of the raw material, the oil and the logistics costs increases we're incurring."

In contrast to Whirlpool, many companies, such as airlines and home heating oil suppliers, say they cannot pass on rising oil costs because of fierce competition.

Petro, a unit of Star Gas Partners LP, has seen the wholesale price it pays for home heating oil soar 90 percent over last year. But it has passed only about half that increase to its customers, said David Shinnebarger, the Stamford, Conn.-based company's chief marketing officer.

"We . . . can't pass it on to the consumer," he said. "If we did we'd have a number of issues: We'd have customer attrition issues, we'd have consumers who wouldn't pay their bills, high accounts receivable."

Petro, which services 524,000 customers from Boston to Virginia, competes against hundreds of smaller companies. "Customers are shopping around," Shinnebarger said. "It's a zero-sum game. Our competitors' customers are calling us. Our customers are calling other companies."

Many publicly run transit systems across the country have to absorb higher diesel fuel costs because of the political resistance to raising fares.

The Washington Area Metropolitan Transit Authority buys diesel fuel for its buses in bulk, resulting in a discounted price, and pays no taxes. Even so, recent fuel bills totaled $1.52 a gallon, much higher than the 97 cents a gallon the agency budgeted.

Metro plans to absorb the added cost by trimming other expenses, and it has not discussed raising bus fares, said Jack Requa, chief operating officer for Metro's bus service.

"We keep an eye on it," Requa said. "There's not much we can do about it."

Construction companies also have been hard hit by rising oil prices because they pay to transport building materials, they buy diesel to fuel off-road vehicles such as cement mixers and dump trucks, and they buy oil-based materials such as asphalt and plastic pipe, said Ken Simonson, chief economist for the Associated General Contractors of America, the trade association for builders of non-residential structures.

These companies typically win a contract for a construction project, such as for a bridge, school, office building or highway, by submitting a bid to do the work at a fixed price, sometimes many months before the work starts. They are therefore generally stuck with any subsequent rise in fuel or materials prices, Simonson said. But they will often try to raise their own prices in future bids, he said.

He said of the recent oil price spike, "For the most part, [companies] have had to eat it and bid higher the next time."