Dropped the Mrs off to meet her friend for lunch and spotted that the nearby big BP station seemed very quiet, so thought I'd fill up. Once in, I saw why it was quiet - all the pumps were coned off, no fuel!

Popped into my usual Tesco nearer home - all pumps fine, no-one in there. Weird. Only thing was the pay at pump wouldn't accept my card which seemed odd as its a Tesco credit card! Fortunately my bank debit card was accepted.

Anyway, my mpg on E10 was 47.64 which is about normal for my usual pattern of driving.

So is the general consensus that there is maybe a small decrease in fuel economy but not noticeable in everyday driving?

From my not very scientific tests I'm finding a fairly large(ish) drop in mpg with E10 about 5mpg or so but will need longer term testing to be sure.

Then again I can't get anything other than Super unleaded around here at the moment, and I had to queue for nearly 2 hours to get that.

 

The suggestion being that a five per cent increase in alcohol content results in a ten per cent increase in fuel consumption makes little sense 

1 hour ago, Blatto said:

From my not very scientific tests I'm finding a fairly large(ish) drop in mpg with E10 about 5mpg or so but will need longer term testing to be sure.

Then again I can't get anything other than Super unleaded around here at the moment, and I had to queue for nearly 2 hours to get that.

 

Having having gone from using E5 Super Unleaded to Regular E10 I’m loosing about 5mpg so far. So my “man maths” is saying E5 Super actually pays for itself ( if you can get your hands on it at the moment) 

10 hours ago, Aldridge Andy said:

Having having gone from using E5 Super Unleaded to Regular E10 I’m loosing about 5mpg so far. So my “man maths” is saying E5 Super actually pays for itself ( if you can get your hands on it at the moment) 

I've now used both and I simply cannot see any difference in MPG.

65 mpg over 210 miles of mixed driving on E10 suggests that there is very little difference. Five per cent of the fuel is less efficient, say by 20 per cent. Half a mile per gallon at worst. You would offset that by keeping your tyre pressures checked.

I think we're jumping the gun a bit on this. Unless you're doing mega mileage you need several months of carefully monitoring consumption under broadly consistent driving conditions to reach any conclusions.

In the past, I've compared "normal" and "super" grade fuels (petrol and diesel) over at least 6 months (and never detected any significant difference when driving a "normal" car.) Also, we are now getting into colder weather where it is not unusual to see a slight drop in mpg.

There is also possibly a bit of psychology at play. We have the idea that E10 is going to be  less economical so that is what we are looking to find.

One of the best things I was ever taught came from one of my college lecturers many years ago. His catchphrase was "Beware of the self-fulfilling prophecy".

On 10/4/2021 at 1:13 PM, Eric Bloodaxe said:

Anyway, my mpg on E10 was 47.64 which is about normal for my usual pattern of driving.

Filled up again today. Mpg on E10 was 48.35 this time which is well in line with my usual experience.

Tallies with mine,  48 in mixed driving.

I can't help but wonder what the Cortina GXL (2.0l pinto that had been warmed) my Dad drove would have thought of it. That motor pinked on anything less than 5*. The progress of computers over carbs I guess.

 

I had a 2 litre Cortina GXL back in 1979/80 had a twin choke Weber carb if I remember correctly.

Was decently quick for a car back then, and I used to run it on 4 star with no pinking that I recall.

 

Still seeing no evidence of lower mpg on E10. Just filled up again and this time my mpg was 51.96.

1 hour ago, Eric Bloodaxe said:

Still seeing no evidence of lower mpg on E10. Just filled up again and this time my mpg was 51.96.

The E10 fuel isn't making any difference at all to my miles per gallon either. I do the same journeys five days a week and I've been watching closely to see how many miles I'm getting from a tank both before and after changing to E10. Absolutely no difference whatsoever.

I've been running on E5 super unleaded for the last 3 weeks, mainly due to the fuel shortage problems around this way recently. I have been getting a consistent 55-57 mpg on my daily commute since then.

I filled up yesterday with E10 will see how it goes for the next few weeks. Looks like it might be a few degress cooler this week so I would expect a slight drop.

 

I'm currently using e5 momentum 99 as it was cheaper than shell Texaco and BP standard e10.  results are mixed on longer trips where the engine gets to full operating temperature there is only a small improvement of around 2% which could be within the margin or error. However on  short trips where the engine never reaches operating temperature the improvement is around 10%. Why could this discrepancy occur? It doesn't make any sense to me. Figures are from car mpg readings.

3 minutes ago, cjay1 said:

Figures are from car mpg readings.

That's your problem right there.

To be fair the error range of the readout should be consistent so the percentage change should be consistent also.when  the tank is empty will be able to confirm with the brim tank method but won't be able to separate cold and warm engine runs.

2 hours ago, cjay1 said:

To be fair the error range of the readout should be consistent so the percentage change should be consistent

I always calculate mpg using the brim to brim method and find the mpg readout on the car is generally over optimistic but not consistently so - anywhere from 2-5 mpg. 

 

1 hour ago, Eric Bloodaxe said:

I always calculate mpg using the brim to brim method and find the mpg readout on the car is generally over optimistic but not consistently so - anywhere from 2-5 mpg. 

I always do the same and I find the the mpg reported by the car is always optimistic.   

I have never bothered about MPG in all honesty, just put £40 to £45 in every month depending on what miles I do. Obviously you don't get as much fuel now for the money but still have the same spend....

Let's see what happens if fuel hits the £1.70/litre plus mark at the end if the year as some are predicting.

I think those prices could force a good few off of the road.

Filled up again with E10 this morning and got 47.28mpg by the "brim to brim" method. Still consistent with my usual range.

This included a break at the coast with heavy traffic both ways, and up the Dales and back to drain down our caravan for the winter, which is always a bit of a nightmare journey, so no economical high gear cruising on this tankful.

Also, this mornings price at Tesco was 141.9ppl, 12ppl more than at the start of October, almost 9.25% rise in a month.

 

 

Yes, think yourself lucky that you don't drive an electric!