This time around, if gasoline prices surge again, the speculator could pay the price, at least in Washington.

When a barrel of oil can shoot to $147 in the summer of 2008, then plunge to the mid-$30s less than a year later, anything's possible.

If the recent past is any guide, it won't be long before prices at the pump go wild.

A busy summer driving season is just around the corner. Stimulus spending has weakened the dollar, which pushes oil higher. And the global economy continues to mend, boosting demand for the precious juice.

Gasoline prices nationwide topped $2.80 a gallon on average last week, and some of the reasons were obvious.

Federal regulators have proposed new rules to limit the role of financial speculation in the futures markets that establish petroleum prices. Over-the-counter energy markets also are being targeted for an overhaul that could restrict the participation of big banks.

Neither measure is a sure thing. The five-member Commodity Futures Trading Commission is said to be divided over its plan for new limits on trading positions. The financial reform bill pushed by Democratic Sen. Christopher Dodd of Connecticut, chairman of the Banking Committee, won't be unanimous either.

Still, changes probably are coming, all the more so if the oil market takes off on another fast ride, predicts Craig Pirrong, finance professor at the University of Houston. "In some respects, the prospects are hostage to oil prices," he said.

Typically, springtime is a rough time at the gas pump.

During nine of the past 10 years, prices have shot up an average of 13 percent in March and April as refiners switched to summer fuel blends and motorists logged more miles, according to AAA.

Oil closed Friday at almost $81 a barrel on the New York Mercantile Exchange, up sharply over the past year, though nowhere near the 2008 peak.

Back then, Goldman Sachs Group Inc. shocked the market with a forecast for $200 oil. That didn't materialize, but some of the long-term factors underlying the prediction haven't changed: Rich new sources remain off-limits to drilling, exploration costs have stayed high, and existing fields won't last forever. Those fundamentals point to higher prices, eventually.

Some believe the oil rally of 2010 has run its course already. Given a stronger dollar in the future and excess refining capacity, gas prices probably will peak for the year around Memorial Day, said Phil Flynn of Chicago's PFG Best Research. "There's plenty of oil out there," he said.

But what if speculators have other ideas? Will they manipulate the market?

"They're innocent," Flynn said. "Totally innocent."

Among market pros like Flynn, it's a common sentiment. From the CME Group Inc. to the swap dealers on Wall Street, financiers often ridicule the idea that excess speculation "causes" price swings. At least one scholar recently declared that no evidence connects speculators with higher volatility. The opposite may be true: Just look at the mild reaction in the heating-oil market over the past few months, despite frigid winter weather.

Main Street, for the most part, disagrees, as reflected in comment letters to the CFTC applauding the proposed changes. Some academics, too, see evidence of excess. Research shows that so-called noncommercial traders such as banks and hedge funds betting on oil account for half the market, up from 20 percent less than a decade ago. Over the same period, price swings expanded dramatically.

At Navistar International Corp., where higher fuel costs can play havoc with orders for the company's big trucks, speculative-position limits sound like a good idea, said Chief Executive Dan Ustian.

"The speculation can cause significant increases," Ustian said. "It creates more problems than it helps."