The New York metro area is much larger than NYC and includes suburbs and smaller cities in Long Island, New Jersey, and Connecticut.
Wouldn't those also be taken into account for the drivers side of the comparison?
Yes, but someone from Long Island or Connecticut who works in Manhattan is unlikely to drive, while someone from those areas who works one town over will almost certainly drive. That will definitely skew these numbers if they don’t adjust for it
Train stations in NYC are much less dense than (for example my own city) Paris subway network.
New-York subway network is impressive for its sprawl, but not really for its efficiency.