Classic car is a term frequently used to describe an older car, but the exact meaning is subject to serious differences in opinion. One school, the broader "antique car club" faction, are very inclusive. Almost any older car in fine condition becomes a classic. The other extreme are the "Concours d'Elegance" supporters, such as the CCCA, who think that only a few thousand "Classic Era Motor Cars" even exist in good condition. They consider nothing newer than 1948 to qualify.
25 years is generally considered a good cut-off age for such terms because it's extremely rare for a vehicle that old to still be owned or used without special consideration for its classic status — by 25 years old, a car will have exceeded its design life by some considerable margin, 10-15 years being the norm barring accidental loss. It will probably need significant maintenance to keep running, and many parts will be hard to obtain through the usual channels. Thus, a non-enthusiast will sensibly conclude that it is not feasible to continue using a car that old for regular driving.
This is not to say that an enthusiast of classic cars might not drive such an old vehicle daily, but that enthusiast will be willing to live with the greater difficulty of so doing or the high cost of restoring the vehicle to reliable condition. Another reason to drive classic cars is that alternatives are hard to come by, as is the case in Cuba, because before the Cuban revolution many rich US citizens lived there, but after the revolution the influx of cars stopped, at least in part due to the United States embargo against Cuba, so people made sure to keep the cars they had in good condition. As a result, Cuba is in the unique position that pre-1959 cars are the standard, rather than an exception, although that is slowly changing. These cars are generally referred to as yank tanks or maquinas and often used as taxis.
Classic Car Club of America Definition
The Classic Car Club of America "claims" to have invented the term Classic car and thus they believe that the true definition of the term is "theirs". According to the CCCA:
- A CCCA Classic is a "fine" or "distinctive" automobile, either American or foreign built, produced between 1925 and 1948. Generally, a Classic was high-priced when new and was built in limited quantities. Other factors, including engine displacement, custom coachwork and luxury accessories, such as power brakes, power clutch, and "one-shot" or automatic lubrication systems, help determine whether a car is considered to be a Classic.
The Club keeps an exhaustive list of the vehicles they consider Classics, and while any member may petition for a vehicle to join the list, such applications are carefully scrutinised and rarely is a new vehicle type admitted.
This rather exclusive definition of a classic car is by no means universally followed, however, and this is acknowledged by the CCCA: while they still maintain the true definition of 'classic car' is theirs, they generally use terms such as CCCA Classic or the trademarked Full Classic to avoid confusion.
United States Legal Definition
Legally, most states have time-based rules for the definition of "classic" for purposes such as antique vehicle registration; for example, Pennsylvania defines it as "A motor vehicle, but not a reproduction thereof, manufactured at least 15 years prior to the current year which has been maintained in or restored to a condition which is substantially in conformity with manufacturer specifications and appearance."
Antique Automobile Club of America
Alternate usage fundamentally equates Classic car with the definition of antique car as used by the Antique Automobile Club of America, who define an Antique car as "anything" over 25 years old. Thus, in this "broader usage" any car over 25 years old can be called a 'classic car'.
There is no fixed definition of a Classic car. Two taxation issues do impact however, leading to some people using them as cut off dates. All cars first registered before 1 January 1973 are free from paying the annual vehicle excise duty. The government Revenue and Customs define a classic car for company taxation purposes as being over 15 years old and having a value in excess of £15,000. 
Classic Car Styling
There was a world wide sea-change in styling in the immediate years after the end of World War II. The 1949 Ford, for example, utterly changed the traditional discrete "replaceable" fender treatment and the radiator "semi-functional" look. From this point on, automobiles of all kinds became "rounded boxes", in basic plan. The CCCA term, "Classic Car" has been confined to "the functionally traditional designs of the earlier period" (mostly pre-war). They tended to have "removable", fenders, trunk, headlights, and a usual vertical grill treatment. In a large vehicle, such as a Duesenberg or Pierce Arrow or in a smaller form, the MG TC, with traditional lines, might typify the "CCCA" term. Since some antique car owners are "investors" it serves the purposes of those clubs to classify a "new look" car as a classic. Thus, it may be a "classic" example of a later period, but not a car from the "Classic period of Design", in the opinion of the traditionalist CCCA faction. Those of the "Antique Car", school of thought would include a 1980 "Anything", that is "clean".
The French 1948 Delahaye is a good the example of a final year of "Classic Era Design".
Among the Marques (Brand names) of cars that are usually considered "Classic" by the "traditionalist group" are:
Auburn - Bentley - BMW - Buick - Cadillac - Cord - Delahaye - Duesenberg - Graham - Hispano-Suiza - Jaguar - LaSalle - Lincoln - Mercedes-Benz - MG - Morgan - NSU - Packard - Pierce-Arrow - Renault - Rolls-Royce - Stutz - Triumph
- Association of Classic Cars Havana, Cuba - Official website of Amigos de Fangio centered in Havana, Cuba, a classic car association of all fans and lovers of vintage cars and motorcycles.
- Classic Rallies - Where Historic rallies and races enthusiasts click - lots of excellent classic car pictures, a complete worldwide events calendar, Classic cars Classifieds and automobilia.
- Classic Cars for Sale - Classic and Collector cars for sale.
- Classics and Customs - Collector cars for sale, forums and resources for car enthusiasts.
- Old Classic Car - A UK based site containing articles, an extensive photograph archive, and free downloads for enthusiasts of classic and vintage cars.
- Custom Classic Cars & hot rods - Online resource for Custom car enthusiasts and collectors
- Classic Cars history - Online resource for classic cars based on car model, year and specification.
- Classic & Dream Cars - Dedicated to Classic Cars and their influence on present Concept Cars' design.
- Classic Nation - A classic car enthusiast website with pictures, classifieds, forum and event calendar.
- My-Classic-Car Community - A classic car restorers/enthusiast resource with videos, pictures, classifieds, forums and event calendars.
- Club Sportiva - A classic, sports and exotic car sharing club.
- Car-in-Pieces - A classic car restorers/enthusiast website with galleries, forums, classifieds, user blogs and event calendar.
-  - A free to enter directory of classic car related websites.
- A Club dedicated to the preservation and enjoyment of all Chrysler products powered by the venerable 'Slant-Six' engine
- Classic Car Buying Guide: What to Know Before You Buy - Autos.com
Hobbyist Cars: Those that aren't necessarily coveted as investments, but are recognized by various State laws as being 'Antique', or 'Historic', generally meaning that they are at least 25 years old