Jan Lundberg, a member of the well-known Lundberg family of gasoline marketing analysts, has sued his sister and mother in the latest chapter in a highly visible family feud.

Lundberg wants the family company -- which publishes the Lundberg Letter, a widely quoted gasoline-marketing and pricing newsletter -- to pay him more than $420,000 in lost income and attorney fees in the long-running battle. Jan Lundberg alleges that the family has interfered in his attempts to set up a gasoline industry research company in Fredericksburg. He also wants the proceeds from the sale of a boat that is tied up in the legal battle.

"I look forward to going to trial, as it seems we must, because I have proof of the attempt to destroy my business," Jan Lundberg said. "I regret the state of affairs but see hope for eventually improved family relations."

His sister, Trilby Lundberg, could not be reached for comment.

The family has been battling for several months over Jan Lundberg's attempt to set up his own business. The feud erupted last year after the death of Dan Lundberg, the colorful, oft-quoted gasoline industry analyst and founder of the North Hollywood, Calif.-based Lundberg Letter and its parent company, Lundberg Survey. His death left the family business with no heir apparent.

After a bitter family battle, Trilby Lundberg, backed by her mother, Mesa, took over control of Lundberg Survey, which produces the newsletter, market surveys and other special reports.

After being pushed out of the family business, Jan Lundberg moved to Fredericksburg to start his own company to produce oil industry market research and policy analysis. He also planned to launch a newsletter last fall using several former Lundberg Letter employes. Lundberg insisted that his company would not be in direct competition with Lundberg Survey.

But Trilby Lundberg went to court in September to stop her brother's efforts, claiming misuse of the family name and resources of the family company. A partial settlement was reached Oct. 14 in which Jan Lundberg agreed not to use his name in the title of his newsletter or in any products or services related to the petroleum industry. A claim by Trilby Lundberg that her brother misappropriated proprietary information while he was a key officer of Lundberg Survey was to be resolved at a Dec. 14 hearing.

Two weeks before the court hearing, however, Jan Lundberg countersued. He said he wanted his sister's company to pay for financial damages his company has suffered from the suit, amounting to $140,000 plus attorney's fees. He has asked for treble damages, plus proceeds from the sale of the family boat.

A court date has been set for next Oct. 15.