I am shocked, shocked I tell you. /s
He has definitely hinted at it before with his "Cost of Car Ownership" video and various cost-of-living analyses.
MMM definitely contributed to my urbanist radicalization, and my political commitment to the cause of urbanism is heavily influenced by financial considerations at both the personal and municipal level. We can all live individually richer lives in urban places that allow us to walk or bike instead of drive, and collectively get more bang for our tax dollar by building dense concentrations of high-value buildings that are serviced by efficient infrastructure.
I inherited a car when I was in undergrad, and sold it before grad school in NYC. I've been car-free ever since and love it on the merits, not just as some kind of sacrifice in order to save money. CityNerd expressed beautifully in this video how transportation constraints reducing optionality is actually a positive: "not owning a car is a form of voluntary simplicity that removes all kinds of extraneous, stupid stuff from your mental space, and lets you spend your braincells on things that actually matter."