No car

You really don't need a car in Japan, at least not for self-transportation. That saves a lot of oil but the trains one uses instead require:
1. nuclear power plants, which are alarmingly unsafe in earthquake-prone "hi-tec Japan"*
2. space. Transportation companies in Japan create their own customers by expanding their networks far into the countryside which then gets paved with concrete and turned into new chaotic suburbs. The farmers who happen to live where suddenly a new city appears are always mysteriously willing to sell their land to the transportation companies. Who operates the train lines controles the developement of the city.

* apart form Play Stations and hybrid cars Japan is less hi-tec than you might think. Read about it in "Dogs and Demons" by Alex Kerr