I did a test of E10, 91 and 95 using Caltex stations on my 2010 Camry Hybrid Luxury over 6 months. The consumption is measured using full fills rather than the car computer. This was recorded over 2 months period for each type of fuel, I fill on average every fortnight and driving about 1000 km during that time. I've found that in $ per km terms at 2011 prices, 91 was the clear winner, followed by E10 and then 95. Difference between E10 and 95 was only a few cents, with E10 being cheaper to run. I've since lost the data logged in the app so I can't give you exact numbers. But 91 was by far the better fuel to get, back in the day 91 was 3 cents per litre more expensive than E10, and 95 was around 10-15 cents more expensive than 91. There's a clear economy difference between E10 and regular fuels in my experience. However, since that time, my local Woolies Caltex have phased out 91 and gone to E10 only...91 RON is really hard to find at a decent price in my area now.