Some place on the California central coast maybe?
Rail connection to LA and SF, temperate weather year round (rarely below freezing, and only then at night, rarely above 80 degrees), lots of good farm land. Only downside is land is so expensive because everybody wants to live here, lol.
And just a couple of questions...would a car free city also be public transit free? (no buses, etc.). Can everybody agree on what exactly a car free city would be?