I have never used premium gas in my vehicles because I saw no real need. I tried it in my 24 Nautilus and did not see much difference. I do not tow or drive under heavy load in hot weather.
BTW, I do use premium fuel in my outdoor power equipment since ethanol free is only available in premium grade.
Some have continued to promote using it and saw a new argument that goes like this.
The 2L in my Nautilus has 2 injectors (one rail, one direct) per cylinder. One downside to direct injection is supposed to be more valve build up since the spray goes over the valve.. As told, at low power situations, the engine uses the rail injectors and under higher load it switches to direct. The claim is that premium fuel allows the engine to use the upper rail injectors longer before switching to the direct injectors. Therefore, valve buildup is reduced. Of course, no claims on how much.
Can someone confirm how the rail and direct injectors actually work?