I have personally tested Shell's E10 on my retired Optra and I did experience a significant decrease in mileage (from 400kms. on a fulltank down to 300kms.), considering that the difference then was just only 10 cents a liter.
I would like to try Petron's E10 though, and if my Sentra would get good results, might as well be a good alternative, considering its now 2 pesos cheaper than regular unleaded.
from shell e10, well, 93 octane, di maganda FC at engine performance sa nissan ko. buti nga naglabas ng e10 ang petron, 95 octane pa.. kasing presyo lang ng lower e10 ng shell.. and gives my car same performance as it would in a more expensive, non-e10 prenium, and sea-oil's g5 extreme(e10-blended)