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Discussion Starter · #821 ·
A week has passed, so it's time for some sort of MPG update.

Once again (as above). Cars are que'd on the road at the Esso station. Thankfully. I didn't need to fill up. Moving on....

Now. I'm pretty sure that the Octane rating of the petrol I'm using, has any effect on the MPG I'm getting. The Ethanol content does have an effect. That said. I think the biggest effect is my style of driving. I'm not saying that I'm indulging in squeezing every last MPG out of the petrol, but it's close. First. The current state of play. Then some notes.

I'm currently averaging 29mpg. The most I've had is 29.4. It has also dipped to 28.7. This includes the daily trip to work and the running around at other times.

In my opinion. The biggest method of fuel saving has been the use of cruise control. The round trip to work and back is 22 miles. I've been using cruise control for 18 of them.

The use of climate control has had a minimal impact on the mpg. I did a trip with it on and a trip with it off. There was a .2mpg difference. It rained on a couple of days. I found that the lights and wipers made no discernible difference to fuel consumption.

As the days roll by. It's getting harder to up the mpg. There's only so much you can do in a 22 mile round trip. The November 30mpg challenge is a 100 mile round trip. That said. The roads are completely different. I've probably reached the limit of what can be achieved at this time. Unless I can come up with another idea......
 

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Amazingly even if I've got no X-type but a V6 75 as you know I do agree on both your conclusions: climate control has a rather indiscernible influence when cruise control is very efficient to maximize mpg.
 

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Discussion Starter · #823 ·
This is a bit of an addendum.

I've now completed two driving cycles on E5. The maximum mpg achieved was 29mpg. The minimum was 28mpg. Each cycle included commuting, shopping and other driving around. Considering that my old Triumph 13/60 Herald was rated at 28mpg. I think that engine technology has certainly improved over the years. Oh. As an extra thought. When I fitted twin carbs to the Herald. I got 35mpg. Moving on....

The question now is: Is the extra cost of E5 petrol worth the money? The only way to find out is to switch to E10. E10 petrol is roughly 15p a Litre cheaper than E5. As of 20 minutes ago. 1 Gallon of E5 cost me £7.55. I'll be using the majority of the petrol over the coming week. This time next week. I'll fill up with E10. Then I'll do another two week cycle.

This is going to be interesting.
 

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Discussion Starter · #824 ·
Update time.

I've put the first of the E10 petrol in the Jag. I did use as much of the E5 as I could (until the Fuel Low light came on) before I filled up. That said. There's still around a Gallon of E5 in the tank. As I don't want the mpg figures skewed by any remaining E5. I'll start the E10 experiment when I fill up again. There's another problem.....

The price of petrol is changing (Going down). As I want a given level of accuracy. I'll need the price of E5 and E10 at the same time. I'll lock those prices into place for the purposes of this experiment. Then it won't matter if the price goes up or down for the duration. As the price of E10 is advertised on a sign when entering the petrol station. I'll need the price of E5. I can only get this when filling up. Thankfully. My Enfield need E5 this week.
 

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Discussion Starter · #825 ·
Right folks. Onto the next stage.

I now have the reference petrol price figures (rounded up).

£1.55 per Litre for E10 petrol.
£1.65 per Litre for E5 petrol.

These prices are from the same time (Today, 16/9/22) and from the same station (Esso) The surprise here is that most pundits have been saying that E5 petrol is 15p per Litre more expensive than E10. Finding E5 that's only 10p per Litre more expensive comes as a surprise. It'll make the final result more interesting.

With all factors taken into consideration. The final average mpg for my Jag comes out at 28.5mpg. Factors include: Weather (Lights, wipers and climate control). Traffic (Open road and traffic jams).

According to Government figures. E10 petrol will return 2mpg less than E5. I have found this myself, but it was on a different set of roads. This time. I'll be using the same ones as the E5 figures. If the 2mpg loss remains consistent. I should get an average of 26.5mpg. It could be argued, that there's enough figures available to come to a conclusion (Potential E10 mpg and the expense (per mile) of E10 and E5 petrol). I'm not going to do that until all the data is available. However. Feel free to Post your predictions and analysis's.
 

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Discussion Starter · #827 ·
I've actually crunched the numbers (based on the currently available data). The result was quite surprising. Although I'm not saying what the result is. Let's just say that E10 doesn't save you as much money as some pundits would have you believe.
 

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Always amazed to read that one has felt a noticeable consumption difference between E5 & E10...
If so there's another difference as well: the more ethanol, the better the car performs. But similarly: between E5 & E10 it's barely discernible.
IMHO on the same journey wind, pressure & temperature are factors to be considered too.
 

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Discussion Starter · #829 ·
The Government said at the outset of E10, that there would be a 2mpg reduction. When I first used E10. I found this to be accurate (What. The Government told the truth for once?). As for performance. I remain skeptical. I've not noticed any difference. Emissions are another matter. E10 certainly runs cleaner. I compared the emissions test from the last MOT (E10 used) with last years (E5 used) and the emissions were a lot lower. I suppose a handy hint would figure here....

Did your car fail the emissions test? Is your catalytic converter on its last legs? Try E10. It just might get an MOT pass!

The weather was certainly a factor to be considered. Over the time period. I had wind, rain and sunshine. I'm in no doubt that the E10 period will be no different. As with all things. There will be a given level of error. What I'm doing isn't exactly scientific. That said. It's close enough to see if E10 is the 'wonder fuel' that the pundits would have us believe.
 

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Discussion Starter · #830 ·
Last night. I filled up with E10. Today. I was supposed to start the 2nd part of the Ethanol experiment. However. A big fat spanner has been thrown into the works. Namely: Road works and the attendant traffic jam. Part of the road I've been using is now closed, while the roundabout they're adding is put in. I've had to use another road (Complete with its own traffic chaos). I'm going to suspend part 2 until I can use the original road again. This experiment needs to be consistant, otherwise any results gained would be worthless.
 

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Discussion Starter · #832 ·
I thought I'd add this as an information tidbit. It doesn't mean much really.

When I started each segment of the experiment. I'd start the engine and then re-set the on board computer. Of course. This would lead to an initial 'spike' in the mpg figures. This 'spike' only happens once and that's on the first run only. The on board computer is left to run (untouched) for the remainder of that part of the experiment. The initial 'spike' for E5 petrol was 31mpg. The initial 'spike' for E10 was 33mpg.

As said. Don't read anything into this. I'm just mentioning it in passing.
 

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Discussion Starter · #833 ·
I'm almost at the half time point in the E10 section of this experiment. I'm not going to say what the current result is, as it's not half time. However. The results are very interesting and have brought to mind a couple of 'claims' made by others who (probably) done the same thing I'm doing.

Claim 1: I'm getting more mpg with E10, than I was with E5.
I think that this claim was based on the initial 'spike', when the on board computer was re-set. I mentioned my initial 'spike' results in the Post above. These mpg figures were only achieved on the first trip out and never achieved again. I think that this claim can be safely dismissed.

Claim 2: Petrol sold as E10 at some stations, is really E5.
I think that there may be something in this. It's a stretch, but it's a possibility. I mentioned a definite 2mpg difference between E5 and E10 (Based on Government figures and previous experience). What if real world mpg figures come out less than 2mpg? On the one hand. That would fall into a normal +- variance parameters? On the other hand. It could all be down to the petrol being the same (E5). I'm using the same petrol station that I've always used. That said. I've no idea what petrol is being delivered. I think the Jury is still out on that one. Now for some observations.

Traffic jams: -1mpg.
Use of kickdown: -2mpg.

Suffice to say. I drive everywhere with the mpg usage display switched on. As mentioned before. The greatest gains are from the use of cruise control. That said. Making up the mpg losses takes more time than it does to lose mpg.
 

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Discussion Starter · #834 ·
It's time for the half time score!

Am I getting fewer mpg on E10? The answer is; Yes. What is the current average? 28.4mpg. Yes folks. You've read that right. I'm currently getting .1mpg less on E10. How is this possible? This average is well within a normal level of error. I have noticed a couple of things though.

Although I've been using cruise control. The level of mpg gain for E10 is greater than the level of gain for E5. In town. The level of loss is the other way around. I use more E10 fuel in town than I do E5.

When cruise control gets used. I've been gaining 6mpg with E10. With E5. I'm struggling to gain 4mpg. It's the urban driving that uses the fuel (as we all know). It just that more E10 is used to get across town than E5. There has to be a genuine reason, but I couldn't say what it is.

There's still another week to go. Things may change.
 
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