Taken from http://www.bestjapancar.com/whyjapan.htm
Fierce competition and introduction of new models every four years, results in strong incentives to new car buyers. Anyone with an ID, a job and a guarantor can drive a brand new car out of a showroom with zero down payment (4 to 6% interest on full loan is the norm).
In other words, purchasing a new car in Japan is relatively cheap, while owning it, is not.
For instance:
-Annual road tax ranges from yen 40,000 for ordinary cars, up to yen 70,000 or more for luxury units.
-Shaken renewal (required every 2 years, after the first original 3 years) from yen120,000 basic models
-Parking space, within a few hundred meter from residence is required prior to purchase of a car
Shaken, a costly combination of taxes and mandatory roadworthy tests, is added to the price of all cars on the road. Shaken renewal is mandatory after 3, 5, 7 & 9 years from first registration.
Beside providing huge income for the government, it also insures every motor vehicle on Japanese road is safe and sound. Shaken price is identical at each renewal and with time, will eventually amount to more than the value of the car itself.