She mastered the names and functions of tools used to build cars and light trucks, and the formula to calculate corporate average fuel economy ratings required by the federal government.
She once called Toyota Motor Corp.'s Tahara assembly plant, on the eastern coast of Japan, amid fishing villages in Mikawa Bay, a mistake because it was much too automated when it was built in 1979. Toyota, fearing a shortage of workers amid Japan's declining birth rates, packed the plant with robots and automation to build the finest Lexus sedans and Toyota models.
"It was not a competitive factory when they built it," Keller would say later.
While she praised the third-generation Ford Taurus as a great car and probably the finest car built by Ford Motor Co., she determined it was too expensive to build.
"Instead of understanding what the marketplace would have paid for a Taurus, Ford designed the car that it wanted to design ... and priced it to earn a reasonable return on its investment," Keller said in an April 1996 speech before a supplier conference. "Now it's paying for those mistakes with rebates, content reduction ... increased incentives and cheap financing and lease deals. The Taurus may reach Ford's sale targets, but it will not reach Ford's profit target."
One of Keller's best sources for research and intelligence was former Detroit 3 executives who went to work for Japanese automakers setting up U.S. operations, as well as U.S. dealers who signed on early to sell Japanese cars starting in the 1970s. Her on-the-ground research made her among the first analysts to warn Detroit of the rising threat from Japan's more fuel-efficient automakers, especially Toyota, Honda and Nissan.
When the Detroit 3 began narrowing the reliability gap with Japan as the 1980s closed, Keller predicted technology would become a key selling point and competitive advantage.
"There are no longer big differentials in size and quality, and cars are becoming look-alike the world over," she told the Los Angeles Times in 1988. "High tech, therefore, is the last competitive edge."
With an encyclopedic memory of the auto industry and a cheerful demeanor, she became a popular guest expert on TV news programs — morning, noon or night. Reporters in small towns and large media markets routinely reached out to her for insight or a quote.
Steve Friedman, onetime executive producer of NBC-TV's "Today" morning program, once told The New York Times that he often invited Keller to be a guest "because she talks English, she knows her stuff, she talks in short sentences, and she's right. What else do you want?"