One of the just four prototypes of the iconic Ford Sierra RS500 Cosworth is heading to an auction, creating an once-in-a-lifetime opportunity for a Ford aficionado.

Chassis #003 was never supposed to survive past the development phase of the production RS500, but somehow it managed to do so along with the other three prototypes. All four of them were painted white and had sequential registration numbers.

Also Read: The Very First Ford Sierra RS500 Cosworth Could Be The Vintage Hot Hatch You’ve Been Looking For

The car you see here was used to homologate the turbo/intercooler/engine upgrades over the ‘standard’ Sierra RS Cosworth, and is even pictured on the official FISA documentation.

Ford produced a total of 5,545 Sierra RS Cosworth models, with 500 of them being the RS500, to homologate the Sierra for the Group A Touring Car racing. The RS500 was an upgraded evolution model, with each one being hand-assembled featuring an uprated Cosworth 2.0-liter turbo engine with 224 HP, better brakes and modified bodywork.

The prototype Ford Sierra RS500 Cosworth is sadly not fitted with its original engine but uses the one from chassis #10 which has been specially tuned by Eggenberger Motorsport. The car is accompanied by an extensive history file that includes its servicing schedule, various invoices, a copy of the FISA documents and a book pack.

Hardcore fans of Ford in Europe will tell you that this is the ultimate Fast Ford of the 1980s and we couldn’t agree more. The holy grail of Cossies will be offered by Silverstone Auctions at their Race Retro Classic & Competition Car Sale on February 22 and is estimated to fetch £60,000 to £70,000 ($77.5k to $90.5k).