Is Premium Gas Really Worth It?

Americans are wasting over $2 billion annually on buying premium gas, 91 octane and above.
That's the conclusion of the American Automobile Association, that ran extensive tests on six different vehicles.
According to Business Insider, while premium gas might upgrade fuel economy and performance, the additional cost isn't worth it.
In short, if your engine isn't knocking when running on regular, you're fine to spend less on the cheaper fuel.