I'll make it short and sweet. What engines can you think of that make more power with Premium than regular, but are approved to and run fine on regular?
The question brought up by osiris reminds me how often people ask if putting premium in their car or truck is a good idea...the answer is almost always "no, not unless it requires it" but there are some engines out there that DO benefit from premium and will produce more power with premium fuel but will run just dandy on regular.
The Toyota GR engines used in the Tacoma, 4runner and others is a good example, it makes more horse power and more torque with premium(+3 hp and 12 ft-lbs on the Tacoma, +31 hp +19 ft-lbs on the 4runner), , but the timing width is sufficient that its approved to run on regular 100% of the time. So, what other engines is the answer to the question: should I use premium? actually a maybe.