Germany is a relatively big country extending fairly far east since the opening of its borders, so I think it would be stretching it a bit if you wanted to see a lot of the country in the 2 weeks that you have available.
It would be more realistic to limit yourself to the south west, perhaps down the Moselle from Luxembourg to Koblenz, then up the Rhine Valley to Mainz. I'd then leave the Rhine and slowly make my way through the Odenwald to Heidelberg, thence south through the Black Forest to Basle and back home again. I think anything much more than that may be a bit too ambitious given the time available but the route that I've suggested would give you a good overall picture of some of quite picturesque areas of the country.
If you'd like more information, I live only about 5 miles from Mainz and the River Rhine and I'd be happy to help.