Depends on where you try to set something up ... noise regulations are pretty tight in Germany, and once you get out of reach of any houses, local green party or similar would probably raise all kind of hell if you dared to pave over half a mile of grass plus parking etc. ...
if you were able to even get close to getting the necessariy permits from all the official places ...
Actually, there are a couple tracks, mainly in the eastern part of germany ... Luckau has one that is in the middle of nowhere, no noise restrictions or anything ... it could use a new layer on the track, and paved parking places, but apart from that, it's actually pretty nice ... if all you're interested in is running you car ...
Of course, apart from that raising the money for such a project wouldn't be any easier, too ...