The trick with vintage cars is to identify models which were great vehicles in
themselves, but which were underestimated (or possibly over-priced) when new, -such as specially manufactured cars by particularly notable manufacturers.
Some Alfa Romeos and Panthers fall into this class. An alternative is to buy
models from quality manufacturers with such low production that all their carsare rare, such as any Rolls Royce or Bentley (especially the coach-built versions), Aston Martin, or Austin-Healey; alternatively low production cars built or significantly modified by Shelby or Lotus. A subdivision of this is vehicles which have such genuinely low mileage that that factor confers rarity. Cars to avoid (except the above-mentioned) are post-war cars with more than two doors, and cheaper mass produced models which were not very good as cars. Also avoid badge engineered cars with grand names which were really only standard models with different hub caps in which the manufacturer carelessly devalued an established reputation, such as Ghia. Possibly because of this eventual devaluation of established names, not many american cars have much real investment potential. Although early Corvette or Thunderbird prices are stable, the market suffers from both hype and over-supply. Most other cars were built in too great numbers to have their values really take off. Only plug into these opportunities if you will have significant contacts within the small coteries of club or enthusiast purchasers. The major exception is the convertible Mustang (only buy the first year of production), a car for which despite there being a reasonably large supply, there will always be willing purchasers.
Although mechanical reliability is completely unimportant, condition is
important. For investment, buy either in mint condition or very cheaply indeed in any condition. However be warned: only buy in the latter category if you have proper restoration facilities yourself. A local garage which has always been very good in servicing your own every-day car will probably be completely out if it's depth in trying to restore a classic. Although not many of these were very complicated, specialised knowledge will be a must in knowing where to get hold of parts or in actually re-manufacturing them from the raw materials. Even so the tenacity required in fully restoring these cars will stretch the patience of most garages to breaking point. Poor restoration can negate returns.
Phenomenon to avoid in cars: Huge profits have been made by getting on a list for a new model from an established manufacturer and then waiting to take delivery in order to flip the right to delivery (or sometimes the car) for a quick profit. This investment potential does not derive from the collecting aspect of the classic car market, -rather it is a pure trading practice which should probably be left to pure traders. Curiously with the exception of Morgan, the value of these cars is almost bound to nose-dive. The secondary market in these cars is for the wealthy user, not the investor. Such user will expect to take the usual loss in selling when he is tired of the car. Try not to be that buyer unless for some reason the car has actually become a classic.
The only situation which looked like an exception to this was the phenomenal opportunity lost by Aston Martin when the factory officially re-produced their most valuable vintage car, the early 1960s DB4GT in a supposedly strictly limited production run. It's investment potential was lost somewhat when the person responsible for the project was heard claiming on the public record that he had company authorisation to make spare chassis plates for his own use. The damage done to the company (now owned by Ford) was not diminished when the chairman of the company carefully avoided denying the claim.
Vintage cars as described may come off recession lows and increase by 15%-40% annually depending on rarity. In reality, use can feed investment potential because it will prompt ownership yearning in others.