The big issue with steam: SAFETY!
In the U.S. in the mid 1800's, most shipwrecks causing many lost lives were steam-powered paddle-wheelers on the Mississippi river that exploded because of pressure problems in the steam engines.
Made sure to have a really good system for PRESSURE RELIEF!
Every home water heater has a temperature and pressure relief valve built right into it.
There were plenty of steam cars in the early 1900s. It would be interesting so see what they used for pressure control at that time.
Anyways, a steam car sounds like lots of fun, but please do keep safety in mind!
