And you thought new car prices were rising.

Mustang

( Mecum Auctions)

A one-of-a kind 1965 Ford Mustang Shelby GT350R was sold at the Mecum Auctions Kissimmee, Florida, event for $4,070,000.

(Mecum Auctions)

It was the highest price ever paid for a Mustang and $220,000 more than what the same car auctioned for in 2020.

Mustang interior

(Mecum Auctions)

The car, serial number 5R002, was built as a prototype for the GT350R competition model, of which 34 were later built. It was tested by Ken Miles of "Ford v Ferrari" fame, who also raced it along with famed drivers Bob Bondurant, Peter Brock, Jerry Titus and Chuck Cantwell.

The GT350R was designed with a modified version of the Mustang's 289 cubic-inch V8 that puts out over 350 hp, an oversized 34-gallon racing fuel tank, and various suspension and drivetrain updates.

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The now fully restored car went on to win 10 races in the SCCA Production-B class before being sold in 1966 to a Ford engineer for $4,000, who later installed an experimental Ford GT40 racing V8 that was included in the sale.

The Shelby has now been twice sold for more than the second-most valuable Mustang, which is the 1968 GT 390 from the Steve McQueen film "Bullitt" that was sold at the 2020 edition of Mecum's Kissimmee event for $3.74 million.