“Indeed, it is likely to deter and further delay investment, if not rule out many refinery investments completely.”

Even so, the current cost of gas — which in real terms is approaching the old peak of $1.42 a gallon in March 1981, or $3.31 adjusted for inflation — has renewed suspicions that the oil industry is looking for ways to keep profits high by delaying much-needed investments. Senator Charles E. Schumer, Democrat of New York, began hearings yesterday on the topic “Is Market Concentration in the U.S. Petroleum Industry Harming Consumers?”

And the House voted yesterday by a narrow margin to penalize any oil companies, traders or retailers found to be charging “unconscionably excessive” prices for gasoline and other fuels. President Bush will probably veto the measure because the White House has said such legislation would amount to price controls.

Experts point to many short-term reasons the United States is running low on gasoline, causing prices to rise: many oil companies are doing maintenance work on refineries; new federal rules make fuels cleaner but costlier; and a string of delays, fires and accidents in the industry have reduced supplies just when drivers are starting to hit the road for summer vacations. Many analysts predict prices will keep rising, then soften later in the summer as demand trails off.

Energy executives dismissed any suggestions that they were intentionally keeping gasoline off the market.

The oil companies say their views on the longer-term prospects for fuel reflect simple economics. Because of the enormous investments required to expand refineries, they say they have no other choice but to re-examine their plans in light of the calls for more ethanol fuel, regardless of how realistic they may be.

“The policy environment has shifted dramatically,” said Mike Wirth, head of global refining business for Chevron. “There is a great risk that has been introduced to projects, predicated upon increasing supplies, that the demand may not be there.”