This week, Gooding & Co. dropped the hammer on the most expensive car ever sold at auction.

It was a 1957 Ferrari 250 Testa Rossa Prototype and it went for $16,390,000 at the Pebble Beach auction. That blew away the previous record of $10,894,000 set in 2009 by another Ferrari.

Gooding and other car auctioneers say the price is proof that collectible cars are now superior investment vehicles (no pun intended). The auction tally was a whopping $78.2 million. Car auctioneers are saying that, unlike the stock market, collectible-car prices just keep going up.

Plus, unlike shares of Bank of America, a Ferrari can be driven around with the top down on a sunny day.

But the prices of collectible cars may be as much a function of the excess capital held by the wealthy" target="_blank" title="a.富有的；丰富的">wealthy than the inherent value of cars. With other investments generating such low returns, cars and other collectibles become more attractive.

Take, for instance, the two charts below. The first (courtesy of Gooding and Sports Car Market Magazine) shows the prices for the most expensive cars ever sold at auction:

The second (courtesy of Emmanuel Saez) shows the average income of the top 0.1%, or the group most likely to be buying multi-million-dollar cars

Average Income of Top 0.1%

Both charts show that the real quantum leap in wealth and car prices was between 1985 and the mid-2000s, which was also when the stock market boomed (though the 1987 Bugatti sale was more of a prelude than proof of the boom).

What's interesting is that while the top incomes have remained roughly flat since 2008, the price of the most expensive car has continued to soar. That may be due to rising wealthoverseas and global demand for collectible cars from buyers outside the U.S.

But it may also suggest that the top prices for collectible cars may be de-coupling from the stock market and top incomes.

What do you think the auction price of the most expensive car will be in 2020?