Here are the registration numbers for passenger vehicles only in 2012 and 2017 (last year DMV stats available). My own theory is that as more New Yorkers become more well-off they buy cars for the freedom and convenience. A 7.61% (+146,505) increase in passenger car ownership between 2012 and 2017 is pretty impressive when you consider how expensive and potentially difficult it is to own a car in NYC. The Alternate Side Parking rules alone are an impediment to car ownership
nyc 2012:
BRONX 227,105
KINGS 408,007
NEW YORK 221,916
QUEENS 671,816
RICHMOND 247,692
NYC 2012 TOTAL 1,776,536
nyc 2017:
BRONX 249,216
KINGS 457,980
NEW YORK 225,179
QUEENS 725,906
RICHMOND 264,760
NYC 2017 TOTAL 1,923,041
https://dmv.ny.gov/statistic/2012reg.pdf
https://dmv.ny.gov/statistic/2017reginforce-web.pdf