This months R&T has an article in its' TECHNICAL CORRESPONDENCE that says it all. A reader writes in that he heard that his 04 Accord will have a 10HP boost if he used premium fuel, and wanted to know if this was just a "pipe dream". The vehicle can be any newer vehicle using a knock sensor according to the article. Here's their answer:
""This one is for real. Modern electronics is good enough that automakers are now writing engine-management software to "follow the knock sensor." That is, the ignition timing, which is already being adjusted by the engine management computer many times per second, is largely determined from what the knock sensor is commanding.
In practice, this means the computer is often advancing the ignition timing (for better power and fuel economy), while the knock sensor announces when the timing is too far advanced whenever knock is detected. Then the computer retards the timing a couple of degrees and the process repeats. Everything else being equal, the higher the fuel octane, the more ignition timing can be run before knock occurs, and thus more power is made. Because the system is constantly at work and finely adjustable, it accounts for the various fuel blends that end up in the cars tank.""
But some of us already knew the benefits of using premium.
