Investors looking for a stable opportunity could be turning to classic cars over more typical commodities such as gold, according to a new report into the value of vintage vehicles.

According to the Historic Automobile Group International (HAGI), the value of classic cars has increased significantly in recent years and is proportionally more attractive than some precious metals.

In 2008, the value of the market covering the world's top 100 classic motors was put at up to $20 billion, with a turnover of around $1.7 billion, based on sales.

Back in 1980, an ounce of gold cost around $416, with modern prices sitting at about $1842. Meanwhile if you had spent a little under $16,000 on an Aston Martin DB5 in the same year and maintained it to a high standard, it could sell for as much as $560,000 in 2011.

Other vehicles like the Ferrari Dino 247GT and the Mercedes-Benz 300SL Gullwing, which would have been available for relatively affordable prices back in 1980, are now fetching the big bucks at auctions.

Of course not all classic vehicles have consistently high values, but the real icons can be sure of attracting serious attention from investors.