Definitions

For the benefit of organizers and participants, the following definitions of many standard car classifications is copied from Wikipedia - the original sources are reliable, and referenced either in or below the article. This is the last section of the full article, which also describes classes for insurance and/or car rental purposes, which does not pertain to any discussion on HotKarz:

Car Show Class Definitions

A different classification system is used for purposes of differentiating vehicles in most car shows. While there is little doubt about the definition of classes that are self-described such as "Mustang" or "Firebird" or "4WD Truck", there is often confusion about the definition of classes that are not as readily understood. The following classes are often used in car shows across America - these definitions are determined either by state regulations, the National Street Rod Association, or have been gathered from other reliable sources:

Street Rod —A motor vehicle, or a reproduction thereof, with a model year of 1948 or older which has been materially altered or modified by the removal, addition or substitution of essential parts and with a gross weight or registered gross weight of not more than 9,000 pounds.

Classic Car —A motor vehicle, but not a reproduction thereof, at least 30 years old, not materially altered or modified by the removal, addition or substitution of essential parts except that such parts represent the original

Hot Rod - Any car rebuilt or modified for higher speed, faster acceleration, or a sportier look. Many automobiles may be called hot rods, including some used in drag racing. They may be composed of used or newly fabricated parts. Can be a kit car.

Custom Car - a factory-built vehicle that has been modified either to improve its performance, often by altering or replacing the engine and transmission, or it may be a personal design by the builder, making the car look unique and unlike any car that might have been factory built. Though distinct from hot rods there is debate among customizers and rodders as to where the line should be drawn. A Custom Car cannot be a kit car, as a kit car is not a factory-built vehicle that has been modified from the original configuration.

Antique — A motor vehicle, but not a reproduction thereof, at least 25 years old, which has been maintained in or restored to a condition which is substantially in conformity with manufacturer specifications and appearance.

Special Interest- a vehicle uniquely distinguishable from the usual, and/or designed for a particular purpose, such as a race car, military vehicle or bus, or built to a specific and unusual theme, either of which would generate interest because of its uniqueness or specialty function.

Kit Car - any vehicle that is created primarily from kit or prefabricated parts, and is a reproduction or replica. An original factory-built vehicle that utilizes prefabricated fiberglass body units to replace worn/damaged original parts is not a kit car.

Muscle Car - a high-performance automobile, built in the 1960's-1970's. The term principally refers to American, Australian and South African models and generally describes a 2-door rear-wheel drive mid-size with a large, powerful V8 engine and special trim, intended for maximum torque on the street or in drag racing competition. Normally was not built with comfort amenities of their counterparts.

Brass Era Car - beginning with the first horseless carriages, named for the brass fittings used for such things as lights and radiators. Starting with the first commercial automobiles of the 1890s to about 1918-19. Includes most Edwardian cars

Veteran Car - any motor vehicle built prior to 1905

Edwardian Car - any vehicle built from 1905 - 1918. Includes all brass era cars

Vintage Car - commonly defined as a car built between 1919 and 1930. The Classic Car Club of America prefers 1925 since it is the pre-classic car period.

Pre-War - beginning with the Great Depression in 1930 and ending after WWII, usually placed at 1948

See also
ACRISS Car Classification Code
Automobile
Car safety and road safety
Car body style
Three wheeled car
Truck classification
Vehicle size class

References
How are vehicle size classes defined? FuelEconomy.gov, part of the U.S. Department of Energy

CANADIAN ENVIRONMENTAL PROTECTION ACT, 1999 Canada Gazette

VFACTS Motor Vehicle Classifications and Definitions Australian FCAI - Federal Chamber of Automotive Industries

Koch, Jeff. "The First Muscle Car: Older Than You" Hemmings Muscle Machines - October 1, 2004, retrieved on 2008-06-30.

The Merriam-Webster definition: "any of a group of American-made 2-door sports coupes with powerful engines designed for high-performance driving."car "muscle car." Merriam-Webster Online, retrieved on 2008-06-30.

"Muscle Car Definition" Muscle Car Club Muscle, undated, retrieved on 2008-06-30.
Sherman, Don. "Muscle Cars Now Worth Millions" The New York Times, June 4, 2006, retrieved on 2008-06-30.

Classic Muscle Cars Library, How Stuff Works, undated, retrieved on 2008-06-30.

"Muscle Car Definition" by Muscle Car Society, undated, retrieved on 2008-06-30.

Gunnell, John (2005). American Cars of The 1960s: A Decade of Diversity. Krause Publications, 47-50. ISBN 978-0896891319.

"Pony Car History" undated, retrieved on 2008-06-30.

Roy, Rex. "Car culture: A child's Pony Car education essential" The Detroit News, February 27, 2008, retrieved on 2008-06-30.