Next month's RM Sotheby's auction in Monterey promises to be one of the most momentous in years. One of the highlights will be an incredible collection of 13 Ferraris worth $18 million, but this selection of Aston Martin racing rarities could top that. Combined, these three legendary race cars could sell for over $20 million. First up is an ultra-rare rare 1989 Aston Martin AMR1 Group C race car, one of only four that were ever made. It's being offered by its first private owner and retains its original carbon fiber chassis.

This particular example has plenty of racing pedigree, having been driven by David Leslie, Brain Redman and Michael Roe at Spa, Donington, Nurburgring, and Brands Hatch. Powering the AMR1 is a 6.0-liter V8 tuned by Callaway Engineering that produces 723 horsepower at more than 7,000 rpm. It's said to be one of the most original existing examples, still wearing its original red, white and blue Mobil 1 racing livery. There's no reserve or estimates, but back in 2014 when it failed to sell at a previous auction it was estimated to sell for between $802,700 and $1,146,730. Next up is a more contemporary Aston Martin DBR9 race car.

Boasting four podium finishes, this 2006 Aston Martin DBR9 is one of only four chassis campaigned by Aston Martin Racing official partner Scuderia Italia BMS during 2006 and 2007. Powered by a 6.0-liter V12, it was driven by Fabio Babini alongside Fabrizio Gollin and made a lasting impression when it took a debut podium at Silverstone in May 2006. After the 24 Hours of Spa, the car was soon retired from racing. To quote the listing: "Rarely does one get a chance to buy such a magnificent factory race car – especially one linked to a team that continues to dominate the track." No estimate has been given for the DBR9, but it will be offered with no reserve.

Last but certainly not least is the 1956 Aston Martin DBR1, arguably "the most important Aston Martin ever produced". This particular example is the first of five factory-built cars and is said to be the most correct of any existing examples. A reproduction engine built by R.S. Williams lurks under the hood, but the car is also being offered with its final Works fitted engine. This DBR1 also took the overall victory at the 1959 Nurburgring and was driven by the legendary racing drivers Carroll Shelby, Reg Parnell, Roy Salvadori, and Stirling Moss. Previous examples have sold for nearly $20 million, meaning this could become the most expensive British-built car to ever sell at auction.