The Department of Energy (DOE) yesterday labeled as "totally inaccurate" a Washington Post story that said the department failed to anticipate that motorists will pay an extra $9 billion for gasoline to the oil companies under a regulation adopted March 1.

The second-ranking regulatory official at DOE, Douglas G. Robinson, said the department used figures as early as February that indicated the rule would cost motorists as much as $11 billion at the pump by the end of 1980.

Robinson, in a prepared statement, offered no explanation why - as late as June 20 - ye was testifying before a U.S. Senate committee that the rule would cost about $3.7 billion.

Robinson said that "the figures reported by the Post were never used at any time."

However, the figures used by the Post were taken from an official DOE document, the final environmental impact statement published in January, just weeks before the so-called "Tilt Rule" was adopted.

On page eight of the introduction of the impact statement, the DOE estimated, "An average price increase of about 1.6 cents per gallon immediately and another 1.8 cents per gallon by 1980, over and above what 2ould be allowed by current regulations, is the maximum likely refiner price increase expected to result from this regulation."

The Post story said that those figures would have meant $3.7 billion in added oil company revenue by the end of 1980, based on DOE"S estimate.

But when the rule went into effect, most oil companies took advantage of it to raise their prices four to six cents a gallon, thus ballooning the price tag of the Tilt regulation up tp $12.9 million by the end of 1980.

Robinson yesterday cited a February DOE documents which estimated "that the maximum possible effect of the Tilt Rule in 1979 would be 4.9 cents per gallon" and 5.1 cents per gallon by the end of 1980, or a total of about $11 billion.

Nevertheless, reporters briefed on March 1 on the impact of the Tilt Rule, were told by DOE officials that it would allow refiners to raise their prices only about 2 cents a gallon in 1979.

And, as late as June 20, Robinson appeared before the Senate Northeast-Midwest Coalition and, in prepared testimony, said that the Tilt Rule "has probably added 3.4 cents (1.6 cents plus 1.8 cents) per gallon in the price of gasoline. That is the same figure used in the environmental impact statement.

A confidential oil company document obtained by The Post showed that one major refiner, Texaco Inc., raised its prices 4.5 cents a gallon for $55 million in extra revenues plus $48.9 million from a controversial provision of the Tilt Rule.

Under a complex formula, the Tilt Rule allows oil companies to make additional revenue on gasoline - beyond crude oil cost increases and operating costs - in recognition of the fact that gasoline costs more to produce than other crude oil products. The intention behind the rule was that it would act as an incentive for oil companies to build more refineries and thus help to head off future gasoline shortages.