Replying to Steam Engine Car

So I saw the thread about the electric car.  I have heard so much about electric car and hybrids, but not a steam engine car.  Of course you might ask about a fuel source... but I think that we could use geothermal energy or this:

http://www.autotropolis.com/wiki/index.php?title=Steam_Engine_Technology_for_Cars

How would geothermal energy get into the car?  I think it could be pumped into a house and then to the car.  Of course the bmw sounds really good (probably better)

The only downside I see is the cost to create this, but of course I don't know anything (I'm a youngster).  So if there are other cons please tell me.

other links:

http://www.articlesbase.com/environment-articles/geothermal-energy-facts-geothermal-energy-pros-and-cons-397739.html

http://www.greensteamengine.com/    (I only skimmed this website, so I don't know that much)

This is not my idea at all, and sorry if this is a repost.