I stopped using E10 "fulltime"a few yrs back when a mechanic at both Ford (my own 6 cylinder company work daily driver) and Toyota (wifes 4 cylinder Camry) both told me that the E10 causes problems because cheap gas stations play with the mixtures and add cheapo methanol based crap to the mix to make a profit out of it.
So i learnt only go to a gas station (like a huge roadside BP station) where new fuel trucks deliver everyday, and only do 3 tanks E10 to 1 x tank premium. I stuck to that principle and havent had an issue.
Interestingly, if u look around the fuel filler on most petrol cars, u shldnt see any stain unless it is redish in colour, but if u use E10 all the time, u see a very blacky carbonned up sludge, so u know what it must be doing inside. Ofcourse, using the "best" magnatec synthetic oil helps too (no mineral grade cheap oil in my cars ever) and change the oil every 10,000 klms no matter what.

I was looking at a brand New diesel vehicle yesterday, and a bloke who bought a new Diesel Pajero a year ago told me he is in a 4 wheel drive club, and ALOT of people are having massively expensive issues with fixing cars due to bad diesel fuels which fark your diesel motors up really bad as well. Car costs today are very high, and the manufacturers warranty does not cover "bad fuel" which is a big get out clause for any car service division.

The next brand new car i buy shortly, will be the Hybrid Camry (half fuel-half petrol) which is a fantastic car, well priced, sweet ride, and internationally recognised as one of the best cars on the planet. Even the taxi drivers say the new hybrid camry uses less fuel than LPG and the new Camry hybrid is a winner. Bring on Julia Gillards new carbon taxing and watch EVERYTHING in the car industry rise sharply to a 10 year high with huge running costs. We need a new government, and for fuels in this country to be more affordable so wholesalers dont play with the fuels which wreck peoples engines.