His DTS sedan will be auctioned online starting on Wednesday and ending on Feb. 19 at Proxibid's website, (https://www.proxibid.com/asp/Catalog.asp?aid=89707). Buffett last year replaced the DTS with a Cadillac XTS.
Proceeds will go to Girls Inc, which offers educational and recreational opportunities to girls in the United States and Canada.
The 84-year-old billionaire's daughter, Susan, is a Girls Inc director, and first lady Michelle Obama is honorary board chair.
Buffett had logged just 20,310 miles in his old car. He commutes roughly two miles from home to his office in Omaha, Nebraska, where he runs Berkshire Hathaway Inc.
The DTS will be autographed by Buffett, and he will deliver the keys personally if the buyer travels to Omaha to pick them up, Proxibid said.
According to the Kelly Blue Book, a 2006 DTS similar to Buffett's and in excellent condition may cost around $11,500, but Buffett's car could fetch more.
In 2006, the winning bid at an auction for Buffett's 2001 Lincoln was $73,200.
Annual auctions for a steak lunch with Buffett, also to benefit charity, routinely fetch seven-figure sums.
Berkshire owns more than 80 businesses, including the BNSF railroad, Dairy Queen ice cream and Geico auto insurance. It agreed last October to buy the Van Tuyl Group, one of the largest U.S. auto retailers.- Reuters