Those paying attention to the classic car auctions in Scottsdale, Arizona last weekend noticed that sales weren't just good, they were dramatically better than 2012 (which was, for the record, quite a bit better than 2011).  The classic car market is growing quickly — perhaps even more quickly than contemporary art — particularly at the very high end.

The Scottsdale auctions, across six auction houses, sold a whopping $223 million in cars last week, up 21 percent from last year's $187 million, which puts the major car auctioneers in a good position going into 2013. "The Arizona events are really a barometer for the year," Alain Squindo, of RM Auctions, told ARTINFO.

Classic car demand is poised to grow even more, according a 2012 report by Barclays wealth and investment management division. In "Profit or Pleasure: Exploring the Motivations Behind Treasure Trends," the bank looked critically at the market for a number of different treasures such as art, wine, jewelry, and cars, and asked high net-worth individuals about their collecting habits. The report contains a number of interesting insights into the car market, which suggest the confidence the auction houses are reporting in high-end vintage sports cars isn't just clever marketing.

The report asked respondents what they had owned in the past, what they owned now, and what they didn't yet own but planned to acquire in the future. Of the ten different types of treasure assets, only two will be more popular in the future than they are today: cars and sculpture (attention: artists). Only 19 percent of respondents owned classic cars currently, but according to the survey, 22 percent plan to own them in the future (compare that to 49 percent and 44 percent, respectively, for fine art).

Cars, furthermore, tend to be the most expensive tangible treasure asset. Among those who own classic cars, the average collection is worth 7 percent of the individual's total net worth (compared to 5 percent for jewelry, 4 percent for fine art, and 2 percent for wine). At the Scottsdale auctions, the most expensive cars sold for just above $8 million. While that might not compare to the $120 million paid for Edvard Munch's "The Scream," the market for cars is somewhat smaller than that for art, so there is less of a range in sale prices.

The question that arises is then, are prices rising because more and more collectors are wanting to buy cars as an investment? That part is unclear, and the answer that does exist is a vague sort of. According to the report, more than twice as many people said they owned cars purely as an investment than owned art (24 percent versus 11 percent for art); however, those in the auto auctioneers industry say they are not seeing a lot of purchasing for investment purposes in terms of buying a car and dumping it in a storage unit. Although many do consider their cars an asset, they also think they are fun.

"There is so much confidence in the car market as a place to collect — I don't like to use the word invest, but the cars have proven to be good investments — but most people buy them because they want to use them, drive them, and show them or vintage-race them," said David Gooding, the president of Gooding & Co. auction house, based in Santa Monica, California. He added that the fact remains that interest rates are so low, hard assets are very attractive for anyone with a lot of cash.

There are a number of caveats for the would-be collector. Cars, even more than art, are expensive to maintain. Not only do they require the same sorts of insurance and general maintenance costs as high-end art, but they also require interaction. You can't leave a car in a storage unit and wait for it to appreciate the way that you can wine, or, to some extent, fine art. Thus, car investors are even more likely than other treasure asset seekers to also be car lovers.

There is also a geographical bias. According to the report, you are more likely to buy a tangible asset like a car as an investment vehicle if you live in a place where the economy isn't as stable as it is in the United States. Treasure assets based on purely financial motivations are common in places like Qatar, Saudi Arabia, and India. However, the majority of car collectors are stateside. "It is primarily an American driven market and it has been for the last 15 years, possibly more," said Gooding, adding that 75 to 90 percent of his clients are American.

Still, whether trends are driven by passion or investment might just be a rhetorical response to the current market — the behavioral finance answer to the passion or investment question is: If the car appreciates, it was an investment. If it doesn't, it was a collector's item. "If prices are rising, they [the buyers] will be happy to think of collectibles as an investment but, if they are falling, they are more likely to say that they bought something because they like it," notes Rachel Pownall, an associate professor of finance at Tilburg Universityin the Netherlands, in the Barclays report.

Currently, prices are rising, and quickly — so car lovers should buckle up.