On the Intermediate difficulty, what's the difference between a regular Nordschleife, 4 hr, and 24 hrs that you get when you have either a bronze, silver, and gold trophies in a row?
Normal Nordschleife is the normal layout that you get in GT4. And its the layout that you can drive your road car on in real life for like 16 Euro a lap. 4hr and 24 hr layout includes F1 track. The 4 hr layout skips a chunk of the full F1 track and the 24 hour layout has almost the entire F1 track incorporated into it.