The Alfa Romeo 6C 2300B and 2500 were among the most expensive cars in the world during the 1930s and 1940s. Fully restored versions of the two cars will be on display at this year’s Concours d’Elegance at Hampton Court Palace on September 4-6, 2020.

The 6C line was produced between 1927 and 1954, taking its name from the six-cylinder engines the model had under their hood. The cars’ engines were designed by Vittorio Jano, an engineer who spent time at Fiat before coming over to Alfa Romeo. They combined with an independent suspension and hydraulic brakes to help the 6C win a number of racing victories over its lifespan including first and second place finished in their classes at the 1937 Mille Miglia; 1st, 2nd and 3rd at the 1937 Targa Abruzzo in Pescara; a victory again at Pescara in 1938; and the top spot at the Targa Florio in 1950.

Their engines weren’t the focus, however. Each of the models’ bodies were built by coachbuilders. In the early 20th Century, coach building was for the world’s elite. The cars with customized cabins were more elegant and expensive than the Dodge Custom and the Buick Series 40.

The Alfa Romeo 6C 2300B going on display this September has a body designed by Swiss coach builder Graber. It’s one of four that Graber built in a cabriolet style and the only existing model with a Mille Miglia-specification engine and chassis. The car was originally ordered by Bruggmuehle Goldach CEO Martin Mueller. At the time Bruggmuehle Goldach was one of the largest wheat mills in Switzerland.

The car underwent a three-year restoration beginning in 2014 and has been returned to the condition it was when Mueller took delivery from Graber.

The 6C 2500 SS succeeded the 2300 in Alfa Romeo’s lineup. The model being shown at the Concours is one of four built by Ghia with Supergioiello – or ‘Super Jewel’ – coachwork, and just one of three that was built on an Alfa Romeo chassis. However, it’s the only one built on an advanced tubular chassis produced by Gilco. The running gear, suspension, and brakes are all period Alfa Romeo 6C components which appear to date primarily from 1948.

The 2500 SS was originally ordered by SIRCA, a dealer in Milan, Italy. The dealer served as Carrozzeria Ghia’s representative for the region of Lombardy. The car found its way to the U.K. in 1959 and just two years later it was up for sale again, listed at just £895 (around £25,000 today). From there it lived in Austria and the Netherlands before arriving in America in 2016. There, it’s owners undertook a 2.5-year restoration process to get the car back to its original specification.