hmmm good question but turbo vehicles for the most part have lower compression then non-turbo vehicles and we need to use premium fuel only. My car clearly states premium fuel only in two places on the car that I am so far aware of.

Could be some performance based vehicles such as the 350z more then likely states premium fuel only. But I can't necessarily say that.

But it seems more performance based cars its always recommended to run synthetic oil just like your told to run premium fuel only.

I'll let someone who has more knowledge on that answer your question in full.