I live as en expat in Heidelberg and, from what I've experienced and seen with other expat friends, living in a "suburb" (or wherever away from some action), without a car gets very lonely and tiresome very fast. Please consider investing in your sanity and either live in the city or buy a car (you can find a decent clunker for a couple thousand euros).
If you haven't already done so, you may want to take a look at this local expat forum:
http://www.toytowngermany.com/forum/...p?showforum=89