NEW YORK (REUTERS) - Warren Buffett's 2006 Cadillac attracted a high bid of US$122,500 (S$166,500), more than 10 times its market value, in a charity auction that concluded on Thursday night.

The autographed DTS sedan, with 32,685km on the clock, was auctioned on the website Proxibid.

A spokeswoman, Dana Kaufman, did not immediately identify the winner.

Proceeds from the auction will go to Girls Inc of Omaha, Nebraska, the city where Buffett runs Berkshire Hathaway.

A longtime favourite charity of the 84-year-old billionaire, Girls Inc offers educational and recreational opportunities to girls in the United States and Canada. It is raising money for an US$18.5 million expansion of a facility in Omaha.

Buffett's daughter, Susan, is a director of Girls Inc's national organisation, and first lady Michelle Obama is honorary board chair.

Buffett will deliver the keys to his old Cadillac personally if the buyer travels to Omaha to pick them up. He replaced the car last year with a new Cadillac XTS.

A 2006 Cadillac similar to Buffett's is worth about US$11,200 on the open market, according to the Kelly Blue Book.

It is common for items once owned by prominent people to sell at auction for well above market value.

In 2009, Proxibid was involved in an auction of items once owned by Ponzi schemer Bernard Madoff, including a blue satin New York Mets baseball jacket with "Madoff" embroidered on the back.

Estimated to be worth US$720 at most, it fetched US$14,500.

Buffett previously donated his 2001 Lincoln Town Car to Girls Inc. It fetched a US$73,200 high bid at auction in 2006.

Annual auctions for a steak lunch with Buffett, which benefit a San Francisco charity that serves the poor and homeless, routinely draw seven-figure sums.