Having returned from our Scotland jaunt, I note two things: This is the first long trip (1500 miles) I have done with the car fuelled entirely with E5, and secondly my average fuel consumption over the distance was 40 mpg, as opposed to the 37mpg or so I had consistently got in previous years.

So either E5 isn't as bad consumption-wise as I was led to believe, or I haven't been giving it as much beans as I used to. The first 1250 miles were all top-down, but the last 250 miles I did with the roof up as it was straight down the M6/M5, there were periodic heavy showers, and quite frankly I fancied a more peaceful drive with less wind buffeting. The consumption for that leg was 42mpg, the car is clearly a bit more aerodynamic with the roof up.

Oh, and fuel in the West Highlands is no more expensive than in Gloucestershire. 205.9p/litre.

Just completed a trip across NI, Antrim Coast and the Republic of Ireland, about 850 miles mostly in heavy rain and strong winds mostly on E5 petrol with a heavily laded car, I started out with a tankful of E10 and filled up with E5 as we went along. I experienced about 2 to 3 miles per gallon more on the E5, but much was on deserted country roads. More noticeable was the increased sweetness in the engine note, it certainly liked E5 more than E10.

Just done some rough calculations and an extra two mpg would be about 6.5% improvement. Fuel cost of E5 over E10 at same station around 7% more. Think I'll give it a go as I'm sure figures can be massaged further

I had some MIL light alerts. My OBD scanner showed “ random intermittent misfire”. Car is a 2002 Plus8 on Gems management. The misfire eas not noticeable. The stats package within Gems basically monitored misfires until a trigger level was reached. Did the usual checks but it still remained. Very occasional not a regular thing. I tried Shell V-Power (97 octane) and that stopped the issue. I also got a couple of extra mpg. I felt the engine ran better as well. Maybe wishful thinking but ....
A few years ago I had a Focus turbo diesel as a commuter. 120 mile round trip, mainly M4. I tried Millers booster in it. A bottle cost about £12 and dosed several tankfuls. Over the time for a bottle my mpg increased and I saved about £36 so a net saving of £24. The car ran well. A mate tried some Millers in his Golf but didn’t see any difference. ( maybe some VW map jiggery pokery? )
The higher octane probably gave better burn and possibly counteracted the random misfire detection. The only possible cause in the Mog I could find at a later date ( checking plugs) was the misfire was reported in cyl3. The ignition lead on that plug was not quite as tight a fit. Magnecor leads so a plus there. I gently squeezed the plug connection and it was as tight as the rest. Now the driving mileage is increasing again I am monitoring the MIL fault frequency. None so far even with 95 octane petrol. I will be continuing to use more 97 though. The mileage covered is not going to increase fuel costs to undesirable. I have not tried the Millers booster for petrol yet and I might try it to see if it has any effect. Might be cheaper than higher octane from the pump. Not a one-shot test though. An extended use to clear the initial stage of use.
As for E10 compatibility, the engine is cleared as ok but not sure about the rest of the fuel system. Flexi pipes, pump seals etc. Time will tell.

I now run Esso Synergy + in the Morgan. It is E5, but in this area should be ethanol free - the biggest worry is all the fuel pipes and seals that are very unlikely to be e10 compliant.

We have also recently returned from a 2,100 mile trip round the west and east coast of Scotland. The best I got was 34 mpg (roof up, wet run up the M6) and the worst 24 mpg and an overall average 29 mpg over the whole trip. Pretty pleased with that as the "usual" is 23 mpg.

Only E10 for me, as I'm too tight to go for Super. I figure the engine's out of BMW's tractor anyway, so probably designed to run on rubbish

Fabulous empty roads and as you say Tim, fuel around the same price as at home.

One of this winter's jobs is to replace my fuel pipe with PTFE-lined hose and proper AN fittings. You can get the fittings to adapt from AN to the standard 7.9mm fuel injector rail from Exo Racing:

https://exoracing.co.uk/an06-to-5-16-7-9mm-efi-hardline-push-on-female-quick-fuel-connector/

I will also see if I can find a length of ethanol-proof filler hose while I'm at it.

E5 was standard at all the petrol stations I stopped at in NI and the Republic of Ireland, didn't come across E10 at all. Petrol costs were little different from the rest of the UK, and based on the exchange rates at the time slightly cheaper in the Republic. The car did feel smoother although it may also be a case of the engine getting really hot and burning any carbon build up off.

Top up of tank and mileage covered gives me around 21 - 25mpg and I'm happy with that on BP Super Plus E5. The variation is directly proportional to the fun factor.

The cost and economy is a non issue for me, it's the unavailability of E5 that concerns me looking further down the road.

I'd be up for a Hydrogen conversion in a few years when it happens.

Whilst I have seen 37 mpg on a long run now I have crise control the weighted avg is 28.7 and the standard deviation 4.5.
I run50:50 on E5 since E10 arrived and that has raised the weighted avg by just under 2 mpg in the last 8000 miles