WASHINGTON -- U.S. demand for oil and refined products — including gasoline — is down sharply from last year, so much so that the United States has become a net exporter of gasoline, unable to consume all that it makes. Yet oil and gas prices are surging.

On Wednesday, oil rose past $106 a barrel and gasoline averaged $3.58 a gallon — thanks again in no small part to rampant financial speculation on top of fears of supply disruptions.

The ostensible reason for the climb of crude prices on the New York Mercantile Exchange, where contracts for future delivery of oil are traded, is growing fear of a military confrontation with Iran in the Persian Gulf’s Strait of Hormuz, through which 20 percent of the world’s oil passes.

While tension over Iran has ratcheted up during the last few months, the price of oil and gasoline has leaped far beyond conventional supply and demand variables. Speculators are piling into the market, torquing the Iranian fear factor into ever-higher prices.

“Speculation is now part of the DNA of oil prices. You cannot separate the two anymore,” said Fadel Gheit, a 30-year veteran of energy markets and an analyst at Oppenheimer & Co. “I still remain convinced oil prices are inflated.”

Consider that light, sweet crude trading on the NYMEX changed hands at $79.20 a barrel four months ago, but soared past $106 a barrel this week, partly on news that Iran would halt shipment of oil to Britain and France. But those countries already had stopped buying Iranian oil. Didier Houssin, the International Energy Agency’s director for energy markets and security, said that “there are alternative supplies that can make up for any loss of Iranian exports,” The Wall Street Journal reported.

Still, oil’s price shot up because it trades in financial markets, where Wall Street firms and other big financial players dominate the trading of oil, even though they have no intention of ever taking possession of the oil whose contracts they are trading.

Since oil prices are the biggest component in the price of gasoline, pump prices are soaring. AAA said that the nationwide average price for a gallon of gasoline stood at $3.58, compared with $3.38 a month ago and $3.17 a year ago. Locally, Fort Lauderdale’s average price for regular unleaded on Tuesday was $3.743, just one cent more than Miami, which averaged $3.735

Defining what percentage of today’s high oil and gas prices is because of excessive speculation, driven by Iran fears, is something of a guessing game. “I put the Iran security premium at about $8 to $10 (a barrel) at this point, which still puts crude at about $90 or $95,” said John Kilduff, veteran energy analyst at AgainCapital in New York. The fear premium is the froth above what prices would be absent fears of a supply disruption — in the $80 to $85 range for a barrel of crude oil. It means that even with the extra cost put on oil from Iran fears, prices are at least $10 higher than what demand fundamentals would dictate.

Why? Financial speculators.

What should the price of oil be if left to conventional supply and demand market fundamentals? Canada’s the largest supplier of imported oil to the United States, which now actually produces more than half of the oil it consumes. Production and delivery costs for a barrel of oil from Canada are about $75 a barrel. The market-fundamentals cost for a barrel of oil is in that ballpark; above that, speculation sets the prices.