Overall great work, but it has a fatal flaw. There are places where the white line (edge of track limits) doesn't reach the wall, and so using all the space available is PUNISHED instead of rewarded, since there is almost no grip outside of the white line. Very counter-intuitive for a street track. I understand you don't want people abusing track limits, but that's what the walls are for.
For example, there is a patch of the low grip surface deep into the braking zone on the left side at the end of the first DRS zone, which causes lockups and spins. Running all the way out to the wall at the exit of the 3-part chicane near the Sphere is a death sentence. Running out to the wall on the right for the corner just before the strip is a sure way to lock the front right tire, and probably spin on turn-in. Same with the chicane at the end of the strip.
If you moved the white line to the edge of the wall, or just made the surface outside of it equally grippy to the racetrack, I would easily give this 5 stars, but as it is, it is incredibly frustrating to push to the limit.