Here's how Wikipeida describes the carfree movement.

"The car-free movement is a broad, informal, emergent network of individuals and organizations including social activists, urban planners and others brought together by a shared belief that cars are too dominant in most modern cities. The goal of the movement is to create places where car use is greatly reduced or eliminated, to convert road and parking space to other public uses and to rebuild compact urban environments where most destinations are within easy reach by walking, cycling or public transport"

It may not be one of the "principles" of the carfree movement but both concepts seem to go hand in hand. Google the following, "Carfree & debt free" and you'll find scores of articles and sites on the same discussion. Most of the push for the carfree movement is coming from environmentalist, urban planners and the like. However, it wouldn't surprise me in the future to see financial planners and other social activists adopt the carfree concept as a solution to becoming debt free. The carfree movment could adopt dept free as a way not only for economic prosperity but liberation from a life time of car payments.
Maybe this is what the movement needs.

How Car-Free Living Can Help You Become Debt Free - Creditinfocenter Blog