On May 5, auction house Gooding and Company announced that it had sold the "unparalleled" 1936 Bugatti Type 57SC Atlantic for an undisclosed value up to $30m.

The anonymous buyer, it said, was "a devoted connoisseur" - one who is now a custodian of one of the rarest and most treasured historic automobiles in history.

The Bugatti's sale comes a full year after the auctioning of the world's previous 'most valuable' car, the 1958 Ferrari 250 Testa Rossa. It was sold in May 2009 for $12.1m.

Regardless of the global economy, it appears that the world's finest classic cars - much like the world's finest sportsmen - are becoming more valuable and expensive year-on-year... and an even better collectibles investment.

The 1936 Bugatti Type 57SC Atlantic, sold for up-to $30m

The Bugatti Type 57SC Atlantic previously sold for $59,000 back in 1971. If we crunch the figures, that's a growth of 17.32% per annum over the last 39 years. A pretty good investment in a classic car.

But what is it about the Type 57SC that makes it worth so much?

The Type 57S/SC remains one of the best-known automobiles by one of history's finest carmakers. The "S" stood for "surbaissé" - or "lowered" - while the "SC" stood for "Supercharged".

Lowering the 57S was a major task. The axle now passed through the rear frame, rather than riding underneath, with a whole new lubrication system required to fit the engine under its low hood.

Along with its incredible engineering, the Type 57S/SC's exceptional rarity is a large factor behind its value. For instance, the 1958 Testa Rossa was one of just 22 of its kind made.

The 57S/SC Atlantic, meanwhile, was one of just four Atlantics ever built with each different from the next. What's more, this example was the very first to leave the factory.

The previous World Record $12.1m Ferrari 250 Testa Rossa

The car was derived from Bugatti's prototype Aerolithe Electron Coupé, which had previously generated much excitement upon its unveiling at the 1935 Paris Auto Salon.

A third factor in the car's price is its provenance. This car, Chassis #57374, has sat in the same private collection for four decades, treated to restoration work envied by collectors across the globe.

It also helped that the car was part of the world-renowned Williamson Bugatti Collection, and that it had won 'Best in Show' at the 2003 Pebble Beach Concours d'Elegance.

Elsewhere, leading research has shown that classic cars are likely to either hold or gain value as investments.

The National Automobile Dealers Association (NADA) found that collector cars worth over $125,000 appreciated at an incredible average of 47% over four years.

Meanwhile, great collectibles investments aren't limited to the classic cars markets. Here are some over collectibles which have shown great value appreciations in recent years...

Three more great appreciating investments (left-right): Bordeaux wine; the Inverted Jenny block of four; and Neil Armstrong's autograph

Investment grade stamps: A block of four 1918 24¢ USA Inverted Jenny airmail stamps

The block was purchased by Bill Gross, the billionaire and "Bond King", for a massive $2.97m in 2006, easily the highest price ever paid for any USA stamp item of any era. The sale trebled the block's previous selling price of $1.1 million in 1989.

The autograph of Neil Armstrong, Apollo 11's first man on the Moon

In terms of figures, rare autographs have shown a growth rate of over 20% per annum. But some are rarer than others - particularly Neil Armstrong. The value of Armstrong's autograph jumped from £475 to £5,500 in 10 years: a staggering gain of 1058%.

Fine wine investment: A fine bottle of premier cru Bordeaux wine

According to a report by respected UK newspaper The Times, Swiss economists Jean-Philippe Weisskopf and Philippe Masset found that that value of Bordeaux wines bought at auction rose by 198% between 1996 and 2009. Of those the best, premier cru, appreciated by 447%.

For more information on appreciating collectible investments, you can sign up for our definitive FREE 27-page report, How To Profit from Collectibles.