The layout is good, the transition from the lower track to the top is well done. The bumpy sections are pretty accurate to the real track with its transitions from old tarmac to new and all the patch jobs over the years. Always loved this old bumpy track. Its hard to get some of the off camber parts into a game but top effort. Well done and I cant wait for the next update.
Low poly mesh, undrivable in some cars, also friction should be between 0.97 and 0.99 as pointed out by David. Certainly wouldnt call this V1 but I'm sure you can improve it, take a look at Tiago's conversions, very nicely done