It's not bad for a first mod. It has a nice flow but with enough variation of turns.
I agree with urielpm that the width is too large.
Suggestions for a next version:
- realistic tarmac with rubber marks on the raceline
- more objects on the side like crowd, stewards and maybe some animals on the grassy slopes.
- green/yellow/blue lights
- grid spots and start/finish line
The road markings thing is my next mission. Also, since I can't remove the bumps from some curves, I had planned to put more marks or some cracks.