No progress on the 350z but I've done some work on the track. Here's a preview:
http://tfric.learnkanji.ca/dump/0001_0750.mp4
There is a lot left to be done with the background objects but I'm happy with the layout so far.
Here's my TODO list for it, let me know if you have other suggestions:
1. More tree variety, especially some larger ones. Shrubs and tall grasses
2. Varying road width, especially around some bends
3. Rocks between uphill switchbacks, more rocky terrain in background
4. Extend the land around the track so less of the skybox is shown
5. New skybox (the current one is not GPL)
6. Fencing around the track
7. Mansion in the background
8. Stream or pond in the background. A wooden bridge or texas gate
9. Attach all the trees to the ground (some float)
10. Rock walls around track near mansion
11. Start/stop gate, canopies and fences like at a rally event
12. Highway crossing