LONDON -- It was the equivalent of finding an old Picasso or an unknown Beatles tape hidden away in your uncle's attic.

Relatives of Dr. Harold Carr found an extremely rare 1937 Bugatti Type 57S Atalante -- a Holy Grail for car collectors -- as they were going through his belongings after his death.

The dusty two-seater, unused since 1960, didn't look like much in the garage in Gosforth, near Newcastle in northern England.

But only 17 were ever made, and when it's cleaned up and auctioned in Paris next month, experts believe it will fetch at least $4.3 million and possibly much more.

Bugatti once represented the height of motoring achievement. The supercar was so ahead of its time it could go up to 130 mph when most other cars topped out about 50 mph.

This particular car is even more valuable because it was originally owned by Earl Howe, a prominent British race car driver, and because its original equipment is intact, so it can be restored without relying on replacement parts.

"It has all the finest attributes any connoisseur collector could ever seek, in one of the ultimate road-going sports cars from the golden era of the 1930s," said James Knight, head of the international motoring department at Bonhams, which will auction the car Feb. 7.

Knight and a small number of Bugatti enthusiasts knew of Carr's proudest possession, but not the eight relatives who inherited Carr's estate.

The orthopedic surgeon, who died at age 89, was described by relatives as an eccentric hoarder who never threw anything out.

The Bugatti marque is famed for its speed and handling and was a frequent race winner in the 1920s and 1930s.

The company founded in 1909 by Ettore Bugatti collapsed in the 1940s after a long string of racing victories.

The rights to the legendary Bugatti name were purchased in 1998 by Volkswagen, which has built the Bugatti Veyron, one of the world's fastest and most expensive cars.