1. Here in Japan, an engine is not replaced when it reaches 50,000miles.
2. All vehicles must undergo a 2 yearly compulsory inspection (shaken) once they are 3 years old. This shaken is made up mostly of tax and fees and can be very expensive if repair work also needs to be done. Most Japanese get their shaken done at the dealer where they bought the car. Dealers ALWAYS use the shaken as a good way to make money, by doing repairs/part replacement even if not necessary. The basic shaken costs from only about US$800 (depends on vehicle size) but get it done at a dealer and it starts from about US$1500~US$3000. The older the car gets, the more the dealer says needs fixing, the more expensive the shaken, so most Japanese just trade in and get a new car. Vehicles over 7 years old are normally scrapped, even though may have only done 70,000 kms or exported as used cars.
3. While the shaken does include emission testing and other tests, it is not severe. For example, I recently purchased a 22 year old Isuzu from a dealer who also did the shaken. The slight amount of rust was just painted over. The day after it passed the shaken, it had to be towed back to the dealer due to engine failure.
4. Vehicles also have to have a yearly service check which includes oil change etc. This is compulsory, unless you can show you did it yourself. Again mostly done at the dealer which equals expensive. To save money and because of expensive oil prices, normally the cheapest oil is used.
5. Accident damaged vehicles are also left at the dealer to repair, the most expensive option, so many are written-off even though the damage may not be so bad or they maybe low mileage.
In general, Japanese do get regular (yearly) maintenance done on their vehicles, but due to dealer and parts costs, they normally take the cheap route on oil qulaity, etc.
Hope this helps.
paddlesnz
JAPAN