Japanese domestic market
The term Japanese domestic market (JDM) refers to the local market in Japan for Japanese-made motor vehicles and components. Within the car and motorcycle hobbyist import scene, this term, and the related term Japanese domestic model, most commonly refer to Japanese-brand automobiles and parts designed and constructed to conform to Japanese vehicle and equipment regulations and to suit Japanese market preferences.
Compared to other countries such as the United States where it is normal for one to purchase a vehicle and drive it for as long as they desire over a great distance, Japanese vehicle ownership culture is heavily influenced by the strict motor vehicle inspection system which makes compliance of vehicles increasingly expensive and difficult as they grow older which forces owners to pay more each year to own the car, sell it, or have it scrapped. The motor inspection rules and the comparatively low average mileage of JDM vehicles have created a burgeoning export business both through traditional commerce and the grey market.
According to the FIA, the average car in Japan travels 9,300 kilometers (5,800 miles) per year compared to an average of 19,100 kilometers (12,000 miles) per year for a vehicle in the United States.
Japanese domestic market vehicles manufactured by a Japanese automaker may differ greatly from their exported counterparts, or the same vehicle manufactured in a foreign country for a different market. The short periods of ownership, less stringent emission standards and a favorable home-market advantage give Japanese automakers an opportunity to refine new technologies and designs in their domestic market vehicles where they appeal to a car-buying populace who look more towards strong innovation than long-term ownership in which the failures of new technologies can greatly affect a brand's reputation.
For instance, the 2003 Honda Inspire, manufactured in Japan and exclusively available on the Japanese Domestic Market, featured the first application of Honda's Variable Cylinder Management. However, the 2003 Honda Accord V6, which was the same basic vehicle primarily designed for the North American market, built in the United States and Thailand, did not feature the cylinder deactivation function. The succeeding 2008 Inspire and Accord V6, which were essentially the same car sans for minor trim pieces would both feature cylinder deactivation, a first in the North American midsize class in which the Accord strongly competes and a feature that was essential for Honda to get right considering the profitability of the Accord and the poor reputation of cylinder deactivation in the United States following the Cadillac V8-6-4 in the 1980s.
JDM cars were limited by a jishu-kisei (gentlemen's agreement) among manufacturers to 280 horsepower (PS) (276 hp) in 1988 and a top speed of 190 km/h (118.1 mph) since the late 1970s, both imposed by JAMA, mostly due to safety concerns and the latter due to concerns regarding bōsōzoku gangs. The horsepower limit was lifted in 2004. However, the speed limit of 180 km/h (111.8 mph) remains in effect (Except Nissan JDM cars that has a speedometer that goes up to 190 km/h with speed limiter), depending on the make and model of vehicle. Many JDM sports cars have speedometers that only go up to 180 km/h (111.8 mph), even though the car would be capable of much higher speeds if not for the built-in limiter.
Vehicles built to JDM specifications may have stiffer suspensions and improved throttle response over vehicles built for different markets, due to differing driving styles and different road types. For example, the USA features long highways where a smoother ride would be preferable, while Japan's roads are short and twisty, where a stiffer suspension is desired for improved handling capability. For the US and European market versions, some features may be removed in order to stay below a certain pricing goal for the car, such as using a conventional rear suspension instead of a double wishbone suspension and lack of electronic devices like Active Yaw Control. Furthermore, engine power of JDM sports cars is sometimes reduced because of stricter emission standards in other countries.
The Japanese market does not apply any of the international VIN systems; instead, Japan uses a Frame Number, which is a string of 9 to 12 alphanumeric characters often[vague] identifying a particular make and model, and a serial number of the vehicle. 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 at all, though different manufacturers use slightly different frame number structures and it is usually easy to determine make from the frame number. Toyota usually uses 7 digits for serial number while Nissan uses 6, for example.
Because a frame number contains far less information than a VIN, JDM vehicles also use a Model Code as a supplement. SV30-BTPNK, for example, wherein "SV30" would have the same meaning as above, and BTPNK would designate a set of features incorporated in the vehicle.
The export of used vehicles from Japan is a substantial industry; stringent roadworthiness inspections make it costly and difficult to keep a car beyond a certain age in Japan, and so used Japanese vehicles are exported, primarily to other markets with left-hand traffic, though Japanese imports are also popular in Russia. A relatively small number are exported to Canada, where a vehicle over 15 years old need not be certified as conforming to Canada Motor Vehicle Safety Standard, and to the United States, where a vehicle more than 25 years old is admissible.
Auto parts 
Vehicle tuners in markets outside Japan often import JDM components for installation on non-JDM vehicles, to attain specific appearance and/or performance characteristics. JDM vehicle body parts, lights, mirrors, wheels, and emblems are among the popular exports for conversion of non-JDM vehicles. In most cases, no significant traffic-compatibility issue arises from the installation of JDM components outside of Japan, but there are safety hazards associated with using JDM headlamps in countries where traffic flows along the right side of the road. This is because all JDM headlamps are engineered for use on the left side of the road; a left-traffic low beam in right-hand traffic blinds oncoming motorists and fails to light the right-side driver's way safely ahead.
- "The Automobile and Society". FIA. Retrieved 7 December 2012.
- "Why Japan finally got its foot off the brake | The Japan Times Online". Search.japantimes.co.jp. 2008-04-13. Retrieved 2009-08-07.
- http://search.japantimes.co.jp/cgi-bin/fv20080413pl.html Why Japan finally got its foot off the brake
- Headlamp traffic-handedness