Cars belonging to the Palmen collection are displayed in the warehouse in which they were stored over the last 40 years, ahead of Friday's auction, in Dordrecht, Netherlands. Image Credit: Reuters

Dordrecht, Netherlands: More than 230 dusty old cars, including some classics worth several hundred thousand euros each, are being auctioned in the Netherlands after being stored for decades by a secretive collector, known only as Mr Palmen.

Dealer Gallery Aaldering became the owner of the collection a few months ago after Palmen, who doesn't have any heirs, was forced to sell it due to his age and medical reasons.

He never showed off his cars but rather kept them a secret, scared people might steal them, Nico Aaldering from Gallery Aaldering said. He described Palmen as "a hermit who enjoyed his cars every day", starting them regularly to keep the engines healthy.

Palmen could afford to buy the cars thanks to smart investments, including in real estate, said Hans van der Pluijm from Classic Car Auctions, which is running the auction.

The collection, which Palmen used to store in a disused church and in two dusty warehouses, contains cars from brands including Alfa Romeo, Lancia, Maserati, Ferrari, Facel Vega, Aston Martin, Jaguar and many others.

"It's a collection you will probably never find in this condition, in this quantity again," said Hans van der Pluijm from Classic Car Auctions.

He estimated most cars will be sold on average for between 25,000 ($27,520) and 75,000 euros, but added that some are worth hundreds of thousands of euros each and one of them, a right-hand drive Lancia Aurelia B24 Spider America, could fetch as much as 2.5 million euros.

Only 240 cars were built of this model, and only 57 of them were right-hand drive.

"It also has a very special design. It's special in every shape and it's wanted in every collection," Van der Pluijm said.

The cars can be previewed after registration on May 26-28.

The online auction has already started and ends on June 7.