Done 50 laps over the past few years in Renault Clios and Megane RS Turbos from
RSR Nurburg (whom I recommend very much).
The other thing to watch out for is loonies on motorcycles. I've had my best laps first thing in the morning, when the track is still a little wet and the bikes haven't come out to play.
As noted above, you are potentially liable for injuries or property damage (including damage to guardrails); make sure you have cover for injuries (see loons on bikes, above).
The track and vehicle dynamics are pretty well simulated in the Forza Motorsport 4 video game (Xbox 360).
I think this video provides a very good overview of the line:
https://www.youtube.com/watch?v=5grymEl6VHI
And finally
I recommend the Haus Marvin in Dottingen. Contact Frau Ackermann via e-mail. Very nice rooms, good breakfast, and about 1/2 mile from the TF entrance:
Tannenweg 11
56729 Döttingen am Nürburgring
Telefon 0 26 91-25 46
Telefax 0 26 91-93 36 49
Mobil 01 78-6 18 82 23
mail:
hotel@hausmarvin.de