A one-off, 21st-century Shelby Cobra concept car is due to be auctioned during Monterey Car Week 2021 (6-15 August).

The car was developed as a collaboration between Ford and racing legend Carroll Shelby as a revival of the 1960s AC Cobra roadsters, making its debut at the 2004 Detroit motor show.

Ford created a number of retro-inspired designs around the turn of the 21st century, including a revived GT and new-generation Thunderbird evocative of its 1950s predecessor. While those models reached production, the Cobra remained a one-off.

Officially dubbed the Ford Shelby Cobra, the two-seater is powered by a DOHC, 6.4-litre, all-aluminium V10 making 605hp. Just four of these engines were built in total, and also found their way into Shelby Mustang and GR1 concepts.

To maximise driver and passenger space behind the V10, the Cobra uses a six-speed manual transaxle sourced from a contemporary Ford GT. This is mounted in the rear of the car, with engine power transferred by a torque tube.

Suspension, steering and Brembo brakes are also the same as the GTs, though the Cobra’s wheelbase is almost 18cm shorter in comparison.

After its unveiling in Detroit, Carroll Shelby drove the car around Irwindale Speedway for 150 miles (241km), performing a number of donuts on the track’s infield before giving it his stamp of approval.

Ford auctioned the concept in 2017 as part of a fundraiser to restore the Fair Lane estate (Henry Ford’s former home). It was purchased by retired Ford executive Chris Theodore, who had been part of the car’s design team. Before the US$825,000 (AU$1.09 million) sale, Ford welded up the torque tube’s splines and driveshaft, and blocked the tube’s access plate. After the driveline and clutch (which had been damaged by Shelby’s donuts) were repaired, the car was made driveable.

Last year Theodore and the Cobra appeared on Jay Leno’s Garage, where automotive appraiser Donald Osborne estimated it to be worth US$1.5 million (AU$1.99 million) in its current state – or up to US$3 million (AU$3.99 million) once road-registered.

The original AC Cobras were a product of Carroll Shelby’s partnership with UK sports car firm AC Cars. Shelby’s version of the AC was initially powered by Ford’s small-block V8, with some later examples modified to run big-block 427ci engines.

Original Cobras have fetched enormous sums at auction. The first-ever Cobra sold for US$13.75 million (AU$18.3 million) in 2016, making it the most expensive American car to be auctioned at that time. Shelby’s personal Cobra, a green 427, took US$5.94 million (AU$7.9 million) earlier this year.

Last week, the first running Ford GT prototype failed to meet reserve on Bring A Trailer, with a highest bid of US$500,000 (AU$664,000). The 2004 GT was used for emissions testing and is limited to 5mph by a Ford-installed computer chip.