Yes, and that's about $100 :) Well okay, it's $91.
Anyway you're right about carpooling. I've noticed that when you're traveling in a group of more than 2 and less than 5, a car is always the best and cheapest option.
Part of this affordable "life on the road" concept might also be the fact that gas prices in the US are about 2.5x as cheap as they are in Europe.
(this is always a fun conversion: https://www.google.com/search?q=1.70+euro+per+liter+in+dolla... not sure if that's the most recent gas price here, but it should be about right. This gives $8.36/gallon, and a quick google for gas prices in New York tells me they pay $3.60/gallon)
I've talked to a New Yorker visiting Ljubljana, he was extremely excited about getting a flat for 1700eur/month because that was about half his NYC rent. It was probably one of the ten most expensive flats you can get in Ljubljana. And we have exorbitant rent prices compared to the rest of my home country.
So yeah, I can easily see how an american would think living on the road is super cheap compared to staying home.
I'm from Europe (NL) and some friends of mine did pretty much that, during college. I don't know exactly how they did it, sorry, travelling's not for me so I didn't pay attention to all the details, but they did pull off travels for very cheap.
One trick is, there's a lot more to trains and public transport (also busses--yes it may not always be comfortable) than first meets the eye. Check out local and national train company websites, ask around at the station where they sell (sometimes you get a really nice person behind the desk, and they'll help you out way beyond expectations, pay attention to what they do and what it's called, so you can order that ticket again). There's probably a bunch of Internet forums sharing tricks as well. I've booked 17h return train trips to Vienna for about 70 euros.
Another trick is sharing rides, if you need to get around in Germany (to and/or from neighbouring countries), try mitfahrgelegenheit.de, it's a carpooling website. At first I thought it'd be crazy unsafe, but I've met the coolest people on those trips.