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Discussion Starter · #1 ·
Been a member for some time but not posted much.
Always poor fuel cons. gettting around 39 mpg and better on long trips obvs.
Been using the better grade petrol for about 2 months and getting a round 41-42.
Last month went on 180mile trip to Norfolk from Oxfordshire, pretty flat country and got 52mpg on way there.
Coming back 3 days later, it dropped markedly and by the time I got home it was on 42mpg, obvs same journey so same terrain, same gentle driving style. It got down to around 35 local driving in the following weeks. Had it's 4th service, 43,000 miles, mid december, no real improvement. Had new front brake discs and pads last week, tyres are fine, pressures correct.
Why is the the fuel "efficiency" so bad, suddenly?

TIA, Caroline
 

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I am afraid that ....
Usually a Small engine + Auto + Cold Weather = [email protected] mpg
Our Sportage Auto will do up to 40 mpg in warm weather but in cold winter temps we are looking at 34/35 mpg.
As iooi posted - traffic can also make a huge difference.
 

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It is surprising how the same route - but in the other direction - can produce markedly different mpg. My first experience of this was as a new driver on what used to be monthly 200 mile trips north to see my parents. With England's prevailing south westerlies, my little Austin 1275 always drank more of its meagre tank on the way back (and how that used to hurt in those days!).

As iooi posted above, as you've eliminated anything mechanical like a sticking brake or low tyre pressures then you are probably looking at the peculiarities of your two journeys. Ambient temperature may have been different, likewise the humidity. Any standing rain water causes drag on the tyres. A road going over an escarpment makes different power demands between it's long shallow gradient and it's short steep gradient. Traffic may feel the same over the two journeys, but even if it's only 10% heavier it will make a difference. So many variables!

Keep an eye on it, I'd suggest. Wait until the weather improves a bit as we head into March. Any sudden sharp drop or rough running might need a trip to your local KIA dealer.
 

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Going back to the original post, I don't think 42MPG is bad. Looking at the real MPG site the official figure is 44 and most people seem to average 34MPG.

Never worry about 1 tank of fuel, it will probably be fine next time.
 

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the temperature is known to matter, but I think that it was the trashy E5 fuel, which they widely introduced not long ago, caused significant wear. I prefer to pay a little more there and continue to use good old E10 gasoline :)
 

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the temperature is known to matter, but I think that it was the trashy E5 fuel, which they widely introduced not long ago, caused significant wear. I prefer to pay a little more there and continue to use good old E10 gasoline :)
EEEEE Lad - You may want to review and edit this post ;)
 
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the temperature is known to matter, but I think that it was the trashy E5 fuel, which they widely introduced not long ago, caused significant wear. I prefer to pay a little more there and continue to use good old E10 gasoline :)
You have got that all wrong.

E10 is the fuel that was introduced in September. It is not "trashy", nothing wrong with it. It meets the required BS standards. The only difference is the extra 5% ethanol content which in my experience so far has made no difference to the mpg or drive of either of our cars.

The E5 introduced in September is different to the E5 sold prior to this. Whilst its still 5% ethanol the octane rating has been increased to 98 to cater for certain exotic cars. Round here its about 10p a litre more expensive, I won't be buying it.
 

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As to why you get different mpg on the same trip, allbe it in the other direction. Head winds, more traffic or colder weather.
My morning 15 mile commute to work would indicate about 60mpg in the Ceed CRDi. My evening commute home would be nearer 40 mpg.

2 significant differences. I normally encountered an approx 1 mile queue of slow moving traffic on the approach road to the M1 on the way home but the biggest difference was the gradient. Home was 600ft above sea level, work was 100 ft above sea level. So pretty much all downhill in the morning and all uphill in the evening.

Another example. Twice a year we visit Scotland, about 430 miles. Destination is at about 600 ft above sea level so no different to home. But in 80% of cases we get better mpg going than returning home, probably about 2 mpg. Same roads, opposite direction but with the prevailing UK winds we tend to get blown there a bit but have to fight our way home.

Rain also makes a big difference. The extra drag of tyres clearing water reduces your mpg.

Since Norfolk is about the lowest part of the country it would be downhill for the OP's outbound trip and uphill for his return. Add in the prevailing south westerlies blowing him there and its certain that the mpg would reduce on the return. By 10 mpg no way.

But looking at what the OP said he got slightly better than his normal mpg on the return trip but significantly better on the way there. Based on this I would suggest there is nothing wrong with the car but the drive there had some peculiarities of climate.
 

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You have got that all wrong.

E10 is the fuel that was introduced in September. It is not "trashy", nothing wrong with it. It meets the required BS standards. The only difference is the extra 5% ethanol content which in my experience so far has made no difference to the mpg or drive of either of our cars.

The E5 introduced in September is different to the E5 sold prior to this. Whilst its still 5% ethanol the octane rating has been increased to 98 to cater for certain exotic cars. Round here its about 10p a litre more expensive, I won't be buying it.
I haven't noticed any MPG difference with E10 fuel either.

I've never noticed a big difference in MPG over the winter either. This is from my spreadsheet of 23 years, with all cars kept outside with a 15 mile commute.

There are probably differences in E5, E10 and Winter v Summer, but there are so many variables in everyday drives it is almost impossible to measure.
 

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You have got that all wrong.

E10 is the fuel that was introduced in September. It is not "trashy", nothing wrong with it. It meets the required BS standards. The only difference is the extra 5% ethanol content which in my experience so far has made no difference to the mpg or drive of either of our cars.

The E5 introduced in September is different to the E5 sold prior to this. Whilst its still 5% ethanol the octane rating has been increased to 98 to cater for certain exotic cars. Round here its about 10p a litre more expensive, I won't be buying it.
Amen to that.

E10 has been used in many countries around the world for years with no issues.
 

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You have got that all wrong.

E10 is the fuel that was introduced in September. It is not "trashy", nothing wrong with it. It meets the required BS standards. The only difference is the extra 5% ethanol content which in my experience so far has made no difference to the mpg or drive of either of our cars.

The E5 introduced in September is different to the E5 sold prior to this. Whilst its still 5% ethanol the octane rating has been increased to 98 to cater for certain exotic cars. Round here its about 10p a litre more expensive, I won't be buying it.
I don't need your lecture on the difference between E5 fuel and new E10 because I know it well. It is enough to read and watch a few videos on YT to see how harmful E10 fuel will be for our engines. So you pour E10 fuel from September and I will stay at E5 because my fuel consumption is noticeably lower plus engine protection.
 

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It is enough to read and watch a few videos on YT to see how harmful E10 fuel will be for our engines.
If its YouTube it must be 100% fact.

E10 petrol with a 95 octane rating will not damage your engine. On older cars (there is a list on the web) the ethanol can damage seals and hoses etc that were never designed to be compatible with this amount of ethanol. But the metal bits will not be affected providing its 95 RON minimum and that is the lowest sold in the UK.

I will be using E5 in our lawn mower because it dates from the early 90's, well before ethanol was added. I use about 10 litres a year thus it will cost me 拢5 a year. Much cheaper than trying to fix the carb and fuel pipes if there are issues. If I bought a new mower it would be fine on E10.

E10 has been used in many countries around the world for years with no issues.
Think that sums it up perfectly. UK cars are the same as those supplied to the rest of the planet but we do have better fuel than many.
 

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If its YouTube it must be 100% fact.

E10 petrol with a 95 octane rating will not damage your engine. On older cars (there is a list on the web) the ethanol can damage seals and hoses etc that were never designed to be compatible with this amount of ethanol. But the metal bits will not be affected providing its 95 RON minimum and that is the lowest sold in the UK.

I will be using E5 in our lawn mower because it dates from the early 90's, well before ethanol was added. I use about 10 litres a year thus it will cost me 拢5 a year. Much cheaper than trying to fix the carb and fuel pipes if there are issues. If I bought a new mower it would be fine on E10.



Think that sums it up perfectly. UK cars are the same as those supplied to the rest of the planet but we do have better fuel than many.
I respect your opinion, but do you also respect my opinion on this subject, because I also read a lot about the differences between the E5 and E10 after my Kia rio started to burn more fuel after the new E10 fuel. It doesn't work like that, your truth is better. greetings馃槈
 

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I respect your opinion, but do you also respect my opinion on this subject, because I also read a lot about the differences between the E5 and E10 after my Kia rio started to burn more fuel after the new E10 fuel. It doesn't work like that, your truth is better. greetings馃槈
I only base my opinion on my own personal experience and good old common sense.

Common sense says that if you only have 90% petrol (E10) of your normal fill of petrol instead of 95% (E5) your mpg would reduce by about 5%. In a car doing 50 mpg that would be a reduced to 47.37 mpg. But the simple fact is the 5% reduction of petrol is replaced by Ethanol which is according to science contains about 30% less energy than petrol. So now you have 90% petrol plus 70% of that missing 5% which is 3.5% for the ethanol, total 93.5%. So theoretically your 50 mpg car would drop to about 49.21 mpg which with the variables of everyday motoring you would never notice.

The following figures are taken from my spreadsheet. Its been used for all our cars since 2008.

Take the wifes Fabia. This time last year on the last 5 fills it was averaging about 48.66 mpg on E5. Filled it yesterday with E10 and over the last 5 fills its averaged 48.48 mpg. The use the car has had has been exactly the same use i.e fortnightly trip to Yorkshire, weekly shopping and some local runs. To me there is no change.

My car is more difficult to judge since it a PHEV and the more you use electricity the better mpg you get. But last year we had 2 holidays to exactly the same place driving there and back on the same roads. One holiday was using E5 and one using E10. About 1,000 miles each time and due the free charging points locally to where we stay all being out of order on both visits the only electricity we used was a full charge before we left home.

In May we averaged about 55 mpg, in September about 56 mpg. Like with the Fabia there was no change.
 

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Well, I have to admit that you made a big impression on me with a handful of statistics. Just like you, for 3 years it has been regularly registering every fuel tank in the application to check the actual fuel consumption of my car. I noticed that from around the end of September, the average fuel consumption of the Kia Rio with a full tank increased by 0.5 liters, because that's how I count it. I understand that the reason is fuel switch from E5 to E10. But maybe you're right and it's worth going back to E10 fuel and seeing if the difference repeats itself. You made me think.
 

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Discussion Starter · #19 ·
Going back to the original post, I don't think 42MPG is bad. Looking at the real MPG site the official figure is 44 and most people seem to average 34MPG.

Never worry about 1 tank of fuel, it will probably be fine next time.
42mpg is bad when you've had 52 on the way up and similar on other long journeys! And with BP Ultimate petrol.
This is a new thing and has not happened before. I've had the car almost 5 years and we've had cold weather and snow before.
 

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The way the post read was that you had only had 52mpg on this one trip and you normally get about 40MPG, which didn't seem too bad to me for a petrol auto.

If you were using the trip computer for the MPG figure then I wouldn't believe the figures, the only accurate way is by working it out using full tanks of fuel.
 
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