"There are 2.6m cars registered in London. 54 per cent of London households have at least one car." -- http://content.tfl.gov.uk/technical-note-12-how-many-cars-ar...

"Tokyo has the lowest number in the nation–0.46 cars per household" -- http://blogs.wsj.com/japanrealtime/2014/08/18/number-of-cars...

I can't find cars per household for Paris, but cars per adult appears to be around 0.5, (https://halshs.archives-ouvertes.fr/hal-01069997/document), so cars per household can't be lower than that.

Hong Kong appears to be truly virtually carless.

Re: HK, not sure if this is cause or effect but the taxis there are much more plentiful and much cheaper than the US. The current conversion looks to be 10HKD = $1.29 USD. A 3-mile cab ride in HK is 60HKD, or about $7.74 ( http://www.numbeo.com/taxi-fare/city_result.jsp?country=Hong... )

In SF it's almost $12: http://yellowcabsf.com/service/cab-fares/

If we scale that to a 10-mile trip, assuming no waiting or traffic, which with SF is $33/hr extra, and in HK it's no charge (just by mileage) IIRC (having them wait is ~$12.38/hr):

SF: ~$31.05 HK: 150HKD=$19.35

This combined with their seriously great subway system ( https://en.m.wikipedia.org/wiki/MTR ) make it very practical to not own a car. You take the subway for short and medium trips, and hop in a cab at the end to get out to a relative's house in the middle of nowhere.

In much of Asia generally, income disparity is such that middle class-ish people can and do hire staff for a lot of things that they couldn't do to the same degree in the US or Western Europe. Thus things like taxis are cheaper.

And Hong Kong is relatively expensive. My experience in southeast Asia is that, in some places, you can hire a car and driver for the day for maybe $50 or so. So--combined with how horrible driving in the big cities there are--many people just have drivers.