Manhattan is obviously the richest borough but people largely don't drive there because it's expensive and annoying to find parking, and there's the congestion charge, and there's always a subway station within a five minute walk.

There might be several reasons for that connection. For example, if you rarely need or use a car it is natural that only those with fuck toy-money would prioritize buying one. They buy it because they might as well, not because they have to.

If public transport was insufficient, or it was easier to use a car, those numbers might look very different.