The steam cars died a natural death due to multiple technical problems that couldn't easily be overcome at the time (cold start, e.g.) Read all about it here:
The Stanleys and their Steamer
This is a hopeful article by a big fan - who hoped steam would make a comeback . . .
Steam cars will be feasible when portable fusion reactors become a reality.
Steam generated by nuke fuel works for ships. Couldn't it be downsized for cars and trucks?