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.

JDM vehicles migrate to other markets through ordinary commerce and the grey market.
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.^[1] The horsepower limit was lifted in 2004.^[2] However, the speed limit of 180 km/h (111.8 mph) remains in effect, 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.
JDM vehicles often differ in features and equipment from vehicles sold elsewhere. For example, Honda has produced many different versions of the B18C 1, B16A and K20A engines for various markets worldwide. This is done due to varying emission regulations in different countries. Internet-based navigation systems have been installed in most vehicles sold in Japan, and as of exporting, those navigation units are beginning to turn up in export markets. Honda's system is called Internavi, Nissan's is called CarWings, and Toyota's system is called G-Book. All three systems use cellular connections from the driver's cellphone for activation, which might be compatible with satellite navigation systems deployed internationally.
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.