The letters are doing less work than most people assume. Japanese Domestic Market is a description of a sales market, so a JDM car is one specified for buyers in Japan, and a JDM part is one made for those cars. Home-market and export versions of the same model can differ in trim, equipment, emissions specification and sometimes engine tune, which is the whole reason the distinction is worth making.
The wider use is cultural rather than literal. Among enthusiasts the term has come to stand for a strand of Japanese performance engineering and the tuning scene around it, particularly from the 1990s, and it gets applied to cars that were sold worldwide. Both uses are in circulation, and they aren't the same claim.
A lot of the engines from that era are admired for being naturally aspirated, while others are the turbocharged units that made forced induction mainstream. If you want the measurements rather than the labels, torque is where that era's reputation actually comes from.
Written by Craig Fearn, Petrol & Ink. Last updated .