The survey indicated taxi and other commercial vehicles are excluded. Looks like the survey looked into non-commercial vehicle registration, which will exclude taxi but wealthy people own a car with chauffeur driver likely are included. Tokyo prefecture will include west side such as Oume, Okutama, and Itsukaichi. Tokyo prefecture will also include Izu Islands which I suspect car ownership will be higher, but number of household will be far smaller compare with 23 ward area of metropolitan Tokyo, that in mind do wonder how much Izu Islands and Tama region or Tokyo influence the number. But number indicates less than half of household in Tokyo prefecture has a car.