The proportion of so-called "high test" used by the state also outstrips that used by the City & County of Honolulu.

State officials acknowledge that the relatively high rate of premium purchases is probably out of line with the gasoline requirements of government vehicles. Last week, after Advertiser inquiries, the state said it would issue new guidance to drivers to cut down on premium sales.

"Yeah, we're probably using more high-test than we need to," said state Comptroller Russ Saito. "Most of them, even the ones using premium, can probably get by with regular."

The savings to state government if it cut its reliance on premium in half would not be huge — less than $25,000, based on a per-gallon difference of 16 cents.

However, the high rate of state-purchased premium gasoline appears at odds with current attempts to persuade consumers to reduce high-grade gasoline purchases. There, the savings are potentially huge — $7 million a year, according to the Federal Trade Commission.

Only about 6 percent of cars sold in the United States require premium gasoline, a grade of fuel required to meet octane standards of high-performance, high-compression engines, according to AAA travel club.

Through August, the state bought a total of 788,063 gallons of gasoline under a contract with Tesoro Petroleum, of which 62 percent, or 488,824 gallons, were regular grade, according to the Department of Accounting and General Services.

State workers bought 283,181 gallons of premium gasoline, 36 percent of all state gas purchases. When combined with 16,058 gallons of mid-grade gasoline purchased, the two higher grades represented about 38 percent of the gasoline used in state vehicles.

Nationwide, about 12 percent of all gasoline sold is premium grade, while in Hawai'i the figure is nearly 21 percent.

State government drivers are advised to use the gasoline recommended in a vehicle's manual, or premium if needed, which would appear to exclude cheaper, mid-grade gasoline, Saito said.

"Probably human nature is to be safe and and purchase the high-test" when drivers aren't sure what a state vehicle requires, he said.

Saito said a new policy now being drafted "might say something like: 'Buy regular unless running regular causes the car to perform substandard,' " in which case workers would be advised to buy mid-grade gasoline.

Saito said the wide range of vehicles used by the state makes it difficult to provide uniform guidance on what gasoline to buy. An inventory of the state's 5,000 vehicles and their gasoline requirements was unavailable last week.

Another issue is that state vehicles often are purchased used, and aren't necessarily as fuel-efficient as new cars, Saito said.

The state also operates a large number of sport utility vehicles in agencies such as the Department of Land and Natural Resources. SUVs aren't as fuel-efficient as sedans, which means they can use more gasoline.

In 2003, the state spent $1.25 million on gasoline through August. That includes $743,283 for regular, $478,457 for premium and $28,781 for mid-grade gasoline.

Senate Transportation Chairman Cal Kawamoto, D-18th (Waipahu, Crestview, Pearl City), said cutting premium purchases could be one way for the state to save money.

"I think it's up to DAGS," he said. "If they want to curtail their costs, they should tell people to buy regular gas."

The question of whether state purchases of premium are excessive comes as gasoline prices near historic highs. Premium typically retails for about 15 to 20 cents a gallon more than regular.

To help consumers save money, the state is encouraging drivers to purchase only the grade of gasoline recommended by a vehicle's manufacturer. While premium gasoline has a higher octane rating than regular, there is typically no added performance benefit in using it unless a car's engine requires the added octane to prevent engine knock, according to the FTC.

At the other end of the gasoline-buying spectrum, the city purchases about 40,000 gallons of gasoline a month, or 480,000 gallons a year — all of the regular variety. Distributed at city fuel depots, the gas is pumped primarily into sedans, Cushman vehicles and a small number of light-duty trucks, said city spokeswoman Carol Costa. The city currently pays $1.57 a gallon, a bulk price that changes periodically.

The Honolulu Board of Water Supply, Honolulu Police Department, Honolulu Fire Department and TheBus purchase their gasoline separately from the city.

Apart from vehicles that use only diesel gasoline, the Board of Water Supply buys only regular, while the Fire Department purchases only mid-grade. Fire trucks typically use diesel. The Fire Department spent $72,421 on gasoline in 2002. Fuel costs for the Board of Water Supply were unavailable.

The Police Department, which operates higher-performance vehicles that may require higher octane, buys only premium. The department spent $2.17 million on gasoline in 2002.

Judging whether state and city agency purchases of mid-grade and premium gasoline are excessive would depend on the kinds of vehicles used, said David Hackett, president of oil industry consultant Stillwater Associates, based in Irvine, Calif., which recently completed a report for the state on Hawai'i's pending gas-price caps.

Hackett said it is human nature to be less concerned about costs when you're not the one paying the bill.

"People aren't always as frugal with their company's money as they are with their own," he said. "The state as a consumer probably didn't realize that it was buying so much premium.

"I bet nobody thought about it."