O'ahu gasoline stations marked up the price of a gallon of regular gas by an average of 56 cents during the last week of June, according to new pricing data the state is now requiring companies to release.

The gap between the retail price for gasoline and the wholesale price was available for the first time yesterday in what becomes a weekly release of oil industry price information by the state Public Utilities Commission.

Lawmakers mandated the disclosure in hopes it will discourage unfair pricing, after the suspension of Hawai'i's controversial gasoline price caps in May 2006.

The data showed that the average O'ahu retail price for regular gasoline during the week ended July 1 was $2.86 a gallon, excluding about 51 cents in taxes. That was 56 cents above the average wholesale price of $2.30 a gallon, which also excludes taxes.

Gas station operators have to mark up gasoline to cover their cost of doing business, but at least two O'ahu operators said they don't mark it up that much. The spread between wholesale and retail prices is typically less than 20 cents a gallon, they said.

"It doesn't make sense at all," said Bob Swartz, who operates Chevron stations in Kane'ohe and Kailua. A 56-cents a gallon margin "would be (as if) I died and gone to heaven."

Barney Robinson, who operates Chevron stations in Kahala and near Honolulu International Airport, agreed.

"Something doesn't add up," he said. "That number is inflated."

It's impossible to draw any conclusions from one week's worth of data. The state hopes the new data will eventually show whether oil profits in Hawai'i are abnormally high. However, state regulators aren't predicting when they'll be able to draw such conclusions.

The markup on gas prices reflects the station operators' expenses plus profit. Expenses were not released yesterday, and, without that, average retail profit cannot be calculated.

The operators' expenses include land, distribution, labor and compliance with environmental regulations, said Tesoro Corp. spokesman Nathan Hokama.

"Prices at the retail level are determined by market competition," Hokama added.

He also cautioned against reading too much into one week of numbers. "It's important to point out that the aggregated data provides a snapshot view and not a long-term view of the retail gasoline business, in which prices fluctuate over time," he said.

Hawai'i drivers typically pay the highest gasoline prices in the nation. That's partially caused by the state's isolated, small market, which isn't subject to the same fluctuations in supply and demand that force Mainland prices to move.

Under the Petroleum Industry Monitoring, Analysis and Reporting program, oil companies must file monthly and weekly reports disclosing in some cases crude oil costs, wholesale prices, gross margins and other figures.

The PUC must disseminate data to the public within two weeks after. However, the law states that the agency must preserve the confidentiality of specific data filed by each company. That means the PUC isn't disclosing data about Hawai'i's two refineries — run by Tesoro and Chevron — such as crude oil costs and production volumes. That's because there aren't enough companies to allow the release of data while maintaining confidentiality, the PUC said.

Without data on crude oil costs and other refining costs, it's impossible to determine the profit margin on wholesale gasoline.

The PUC said yesterday's report was based on data filed by oil companies, but would not provide further analysis. PUC spokeswoman Lisa Kikuta said the agency will look into ways to provide more data in future reports.

"We will be looking at how to group that (refinery) information so that certain data can be shared and disclosed," she said. "Going forward, we're going to strive to improve the value of these weekly publications."

Reach Sean Hao at shao@honoluluadvertiser.com.