though you may be purchasing 94octane, carefuly where you buy it from. it may contain 0 ethanol as most gas stations state, however most gas stations do have the ability to switch the pumps if the 94 tank is running low. also, the area you buy it from is important too. say its in an area where most ppl will ONLY be buying the lower octane gas, that means the 94 octane gas station tank is gas that is fairly old. old gas isnt any better.
from where i work (a different car manufactuer), the engines are more sensitive to ethanol. so far, esso 91/92 seems ok, shell 91/92 has no ethanol as advertised. im not too sure with petro canada and i believe in the vancouver lower mainland area, they got rid of the 94 octane all together.
I use Shell 91 VPower in all my engines except family van. It even works much better in my Toro slowblower that had problems when I used regular with ethanol, carbs flouter got stuck after first winter, no problems in last 3 years
I get Esso 91 or Petro if I can't find an Esso. I get worse overall mileage on Shell 91 than Esso.
I get better city mileage with shell but better highway mileage with Esso.
2006 IS 250 AWD Blue Onyx Pearl - F Sport Shocks with H&R springs, F Sport Front & Rear Sways, JoeZ intake, M2 Axle back, 18" Enkei's in the summer, Stock 17" in the winter, 5000K HIDs, 5000K LED fogs, White 5SMD led city lights.
no statistics no care, talk is just talk
there are so many factors that come into play with mileage you can't just say "I get better here than there"
theoretically vpower will give more mileage because there's more energy and less (no) ethanol