They can be, but you shouldn't treat classic cars as an investment. Unlike, for example, stocks, you can't analyze how the market will behave and whether or not it will increase in value. While there's always a bit of speculation involved when investing, speculating on the classic car market is very risky, if not downright reckless. Not to mention, there are a lot of maintenance costs involved, and the profit you make might not cover that. Our advice is to buy whichever classic car your heart desires, treat it well, enjoy it, and not worry too much about whether or not you make money out of it.