i didn't have much problem beating it with the tune for the amuse s2000 that is offered here at this site.
Check here.
I think S-10 was the last one I cleared also along with S-7 - those were the hardest but they can be done since the last update - stick with Standard Physics and you'll get it soon.
You can pass S7 and S10 with the Nissan GTR, which you already need to buy for some of the other challenges. Probably not the best car for it, but definitely the cheapest route to go.
I beat S10 with the Ford GT LM (pro physics).
It's a tough event.