For decades, the world's wealthiest classic car collectors have competed for the rarest models from brands such as Aston Martin, Ferrari, Porsche and Lamborghini.
Yet one of the biggest success stories in the classic car market belongs to a far more familiar name: Ford.
High-performance 'Fast Fords' from the 1970s, 1980s and 1990s have become highly desirable among collectors, with the Ford Sierra RS Cosworth leading the way.
When it launched in the 1980s, the Sierra RS Cosworth cost just under £20,000. Adjusted for inflation, that's around £60,000 in today's money. Four decades later, the very best examples are now changing hands for well into six figures.
That demand will be on display later this month when six rare Sierra Cosworths are offered for sale by Iconic Auctioneers at Silverstone. Together, they are expected to achieve around £1 million.
Rare RS500 models lead the sale
The headline cars are three examples of the legendary Sierra RS500 Cosworth. Built purely to satisfy motorsport homologation rules, just 500 road cars were produced between March and July 1987.
The star of the collection is car number 468, finished in white and showing just over 16,700 miles. It is one of only 56 white RS500s built and comes from the renowned BonkeRS Collection. Auctioneers expect it to sell for between £150,000 and £200,000.
Another RS500, number 195, is finished in black and has covered 44,599 miles. Complete with extensive history and factory documentation, it carries an estimate of £80,000 to £100,000.
The third RS500 is even rarer in Moonstone Blue, one of just 52 produced in the colour. Despite covering more than 67,000 miles, it remains largely original and is expected to sell for £90,000 to £120,000.
Also crossing the block is a genuine Group A racing RS500 with competition history in both the British and Australian Touring Car Championships. Its estimate of £400,000 to £450,000 makes it the most valuable car in the sale.
Time-warp Sierra could rival the RS500
One of the most remarkable cars is a standard 1987 Sierra RS Cosworth finished in Diamond White.
Unlike the rarer RS500, this three-door Cosworth has remained in the same family since new and has covered just 6,242 miles.
Stored in a private garage since 1988, it still displays its original 1988 tax disc and has only been lightly recommissioned twice in recent years. Its exceptional originality has resulted in an estimated value of £100,000 to £120,000.
Completing the collection is a 1991 Sapphire Cosworth Rouse Sport 304-R, a rare road-going conversion built by touring car legend Andy Rouse. Believed to be one of only two Diamond White four-wheel-drive examples still registered in the UK, it is expected to sell for more than £50,000.
Rob Hubbard of Iconic Auctioneers said the continued popularity of performance Fords has helped drive demand among collectors.
He said: "Performance Fords continue to command huge affection and serious collector interest, and this group of Sierras is a wonderful reminder of why.
"From highly original road cars to a Group A racer with period touring car history, these are cars that speak to enthusiasts at every level."
Why the Sierra Cosworth became a legend
The Ford Sierra RS Cosworth made its public debut at the Geneva Motor Show in 1985 and was developed so Ford could compete in Group A Touring Car racing.
Powered by a Cosworth-developed 2.0-litre turbocharged engine, it quickly earned a reputation for performance that embarrassed far more expensive sports cars.
The even more extreme RS500 arrived in 1987 with improved aerodynamics, a more powerful version of the turbo engine and hand-built modifications by Aston Martin Tickford.
Although just 500 RS500s were produced, Ford built more than 5,500 Sierra RS Cosworths in total. Today, the RS500 is widely regarded as the ultimate Fast Ford of the 1980s.
Why values have risen so dramatically
Prices for Sierra RS Cosworths had been steadily climbing for years, but the market accelerated dramatically during the early 2020s.
In 2022, an exceptionally original Sierra RS Cosworth sold for more than £130,000, setting a new benchmark.
The following year, a near-perfect RS500 with just over 5,000 miles achieved almost £600,000 at auction, becoming one of the most expensive road-going Fords ever sold.
While that result remains exceptional, it has helped lift values across the market. Today, outstanding RS500s regularly command well over £100,000, while the very best standard Sierra Cosworths are now approaching similar figures.
For comparison, many desirable Series 1 Jaguar E-Types typically sell for between £70,000 and £150,000, showing just how far the iconic Fast Ford has come from its humble beginnings as a high-performance family car.