The term "Japanese domestic market" (JDM, also "Japanese domestic model") refers to Japan's home market for Japanese vehicles and components. For the importer, these terms refer to Japanese-brand automobiles and parts designed to conform to Japanese regulations and to suit Japanese buyers.
Compared to the United States where most drivers keep vehicles for the life of the car, Japanese owners contend with a strict motor vehicle inspection system which forces them to pay more each year to own a car and to sell or scrap it. Compliance encourages a burgeoning export business in legitimate and gray markets. According to the Foreign Import Association, a car in Japan travels a yearly average of only 9,300 kilometers (5,800 miles), less than half the U.S. average of 19,100 kilometers (12,000 miles).
Japanese domestic market vehicles may differ greatly from the cars manufacturers built for export and built in other countries. The Japanese car owner looks more toward innovation than long-term ownership which forces Japanese carmakers to refine new technologies and designs first in domestic vehicles. Failures greatly affect a brand's reputation. For instance, the 2003 Honda Inspire manufactured for Japanese drivers featured the first application of Honda's Variable Cylinder Management. In the United States in the 1980s, Cadillac had attempted the same technology but with poor results. Given the bad Variable-Cylinder reputation, Honda built the 2003 Honda Accord V6 -the American version of the Inspire- without the cylinder deactivation function. In 2008, Honda successfully re-introduced Variable Cylinder Management in the Accord to American buyers.
In 1988, JDM cars were limited by voluntary self-restraints among manufacturers to 280 horsepower (PS) (276 hp) and a top speed of 190 km/h (118.1 mph), limits imposed by the Japan Automobile Manufacturers Association (JAMA) for safety. The horsepower limit was lifted in 2004 but the speed limit of 180 km/h (111.8 mph) remains in effect. Many JDM cars have speedometers that register up to 180 km/h (111.8 mph) (certain Nissans go up to 190 km/h) but all have speed limiters.
JDM cars usually have stiffer suspensions and improved throttle response because the roads wind over hilly terrain. Conversely, American drivers prefer smoother rides because of interstate systems covering thousands of miles. Japanese manufacturers also remove certain innovations to keep US and European prices down, such as using a conventional rear suspension instead of a double wishbone suspension and eliminating electronic devices such as Active Yaw Control. Finally, JDM engine power is sometimes reduced because of stricter emission standards in other countries.

VIN

Japanese carmakers do not use a Vehicle Identification Number as is common in the United States and elsewhere. Instead, Japan uses a Frame Number, 9 to 12 alphanumeric characters identifying model and serial number. For example, Frame Number SV30-0169266 breaks down as "V30" identifying the model as Toyota Camry/Vista x30; "S" identifying the engine (4S-FE), and 0169266 being the serial number of the vehicle. Vehicle make is not identified but slight number variations can identify the carmaker, i.e. Toyota usually uses 7 digits for their serial numbers while Nissan uses 6. Because a frame number contains far less information than a VIN, JDM vehicles also use a Model Code. As an example, SV30-BTPNK breaks down as "SV30," which means the same as above, and BTPNK which designates a set of features incorporated in the vehicle.

Vehicles

Because Japan's roadworthiness inspections make it costly and difficult to keep an older car, used Japanese vehicles are exported primarily to other left-hand traffic markets and to Russia. Few go to right-hand-traffic United States and Canada, where a vehicle must be at least 25 years old before the owner can legally forego U.S. roadworthiness compliance while in Canada the car must be at least 15 years old.

Auto parts

JDM components such as lights, mirrors, wheels, and emblems are often imported for installation on non-JDM vehicles for appearance and performance enhancements. However, all JDM headlamps are engineered for use on the left side of the road which means a left-traffic low beam in right-hand traffic blinds oncoming motorists while failing to cast adequate light for the driver.