Pretty much anything that billionaire Warren Buffett says or does makes news, it seems. So last week, when the influential investor was photographed sitting alone in a new Subaru Outback, a hungry blogger at AutoEvolution turned it into a story, which then went viral, including this post explaining how the no-nonsense Subaru is a perfect fit for the Wizard of Omaha’s frugal investing style. CNBC tweeted the news to its 1.5 million followers and Subaru even jumped on board, posting the grainy photo and story on its Facebook page.

Buffett, whose modest tastes are well-known, was flabbergasted by the attention — especially because the story was wrong. “I’ve never driven a Subaru in my life,” he told me in an interview. On the day in question (July 8), he happened to be sitting in the passenger seat of the Outback — a courtesy car provided by organizers of last week’s Allen & Co. conference in Sun Valley, Idaho — while his daughter went inside to pick up their room keys and credentials. “I stayed in the car and somebody snapped that picture,” he said.

Everybody knows Buffett is partial to American nameplates anyway. “Once, in the 1960s, when the (Volkswagen) Beetle came out, I had one for a year or so,” he told me. And in high school, he was half-owner of a Rolls Royce. Mostly, though, he favors cars made by General Motors GM -0.74% or Ford Motor F -0.88%. “The truth is, I only drive about 3,500 miles a year so I will buy a new car very infrequently.”

In fact, his 2006 Cadillac DTS DTSI -0.96%, which had just 19,000 miles on it, was barely broken in when he became convinced recently it was time to replace it.

The sales pitch came from none other than GM Chief Executive Mary Barra, who had flown to Omaha in mid-May to meet one of GM’s largest shareholders amid a growing safety crisis that threatened to stall the automaker’s comeback. The meeting came around the same time Buffett’s holding company, Berkshire Hathaway, disclosed that it had cut its stake in GM by 25 percent, to 30 million shares, during the first quarter.

As they motored through Omaha in his eight-year-old DTS, Buffett asked what made the new generation of Cadillacs better. “She really let me have it,” Buffett said. “She told me about 50 things that were better” than his current set of wheels. “By the time we got to lunch — and it’s only 5 or 6 minutes — she sold me.”

Worried, however, that the world’s third-richest man, worth $65.8 billion, might not get a good price, the 83-year-old Buffett dispatched his daughter, Susie, down to Huber Cadillac in Omaha to make the purchase on his behalf. There she was met by a young saleswoman named Madison Willers, who Buffett said “couldn’t have been more helpful.”

Barra had suggested he buy the widely acclaimed Cadillac CTS sports sedan, but Willers convinced Susie that her anonymous dad might want to go a different way. In a letter to Barra later, Buffett wrote: “My daughter said that her dad’s ‘car-guy friend’ (that’s you) said he should buy a CTS, but Madison said the XTS would be more appropriate. I think this reflects an evaluation on her part that from Susie’s description I must be hopelessly over the hill (a unanimous view among my family).” He also praised the owner of the dealership, Brett Huber, describing him as “extremely accommodating.”

Barra penned a hand-written response: “Dear Warren, Thank you very much for buying a GM vehicle. The XTS is a great choice! If you ever have a question or concern, please let me know. It was great to hear that Madison and Brett demonstrated our company value — the customer is our compass. I will look forward to riding in your XTS the next time I visit. Thanks again, Mary Barra.”

Did he get a good trade-in price on the old DTS? Nope. He donated it to Girls Inc., a charitable organization for girls.

As for Barra and General Motors? Buffett thinks she’s “terrific” and said he offered her some advice, based on his own experience steering Salomon Brothers through a devastating bond-trading scandal in the early 1990s. “When you have a problem, get it right, get it fast, get it out and get it over. That’s what I told her.”

He says GM’s current crisis will pass. “In the end, it will be what they do over the next 10 years that counts. They’ve got to deal with the past. It’s not easy, but she’s the person to do it.”

I'm sure that Cadillac will enjoy any halo effect from his choice.