"The concept is not about travel by car. It is about active transport (walking, cycling) and the use of public transport. The goal is that this combination of modes would offer a reasonably sized catchment area in which people, jobs and services, including recreational opportunities and nature, are accessible."
from:
https://theconversation.com/people-love-the-idea-of-20-minute-neighbourhoods-so-why-isnt-it-top-of-the-agenda-131193