There are several valid reasons for the replacement used JDM engines in the United States Domestic Market and other worldwide market engines. However, the major reason is that in Japan, all vehicles should pass a car inspection, known as Shaken. This inspection will only determine, whether the car is still appropriate to be driven on the Japanese roads. Shaken can be extremely costly and often it will drive the value of the vehicles to zero. The older a vehicle gets, meeting the Shaken standards may involve thousands of yen.

Traditionally, the Japanese vehicle owners do not like to get concerned with the auto repairs of their vehicles. This is because auto mechanics charge their customers with a hefty repair charge for simple repairs, particularly to meet the standards set by Shaken. If your car fails in the Shaken inspection, then it will be considered illegal to drive on the Japanese roads.