What would buy you much is mixed neighborhoods (aka: the 15 minute city - everything you need for your daily life is within 15 minutes walking distance), because this will eliminate many trips. But mixed neighborhoods work better with higher density - because a supermarket in a low density place cannot be within 15 minutes walking distance.
Also: This is about NYC. How would you even go about reducing Manhattens density to a level where no road is used by less than 2000 (or 4000) people per hour during rush hour?