Posted this elsewhere but thought you guys might be interested. 95 RON in the UK is equivalent to the US 91 Octane stuff I believe. We can't get any less than that at most forecourts.
Been tracking the fuel consumption on my Honda Insight ES (1.3 i-VTEC IMA) since buying it 5 months ago. I have the trip computer automatically reset each time the tank is filled. Generally been buying whatever is cheapest in the local area, or whichever garage I get to first after the fuel light comes on.
On supermarket (well - sainsburys, tesco and Morrisons) fuel the trip computer consistently reports 3-5 mpg higher mpg than calculated using the old brim to brim technique. Most of my fills have been at a supermarket with a few at the named brands.
For Shell and BP the computer consumption seems to be within 1-2 mpg of actual. It still over-reports the trip mpg but not by as much.
I'm going to try sticking to the branded fuels for a while to see if this holds true for a larger data set. I could potentially use Total, Esso or maybe Texaco too (though Texaco is unlikely as they're always about 4p more expensive than the others). Always been sticking to 95RON, as per the manufacturer's instructions.
I've seen people claim better mpg on branded fuels but always took it with a pinch of salt, as I figured the oil companies would be supplying the supermarkets anyway. Never seen anyone mention detecting a difference by calculated vs actual fuel consumption. Anyone else noticed similar.