Supermarket Fuel

[YarisHybrid2016]

I'm starting this thread as someone had a question about it, and wanted to post my experience here (based on Gen.3 Yaris).

First off, ethanol is evil. Normal road cars don't run well on it.

My experience with E10 has been rubbish. It causes significantly higher fuel burn/lower MPG due to the ethanol having a lower calorific value vs. the equivalent volume of petrol. The ECU compensates by injecting more fuel.

To quote Scotty from Star Trek: "Ye can'ne beat the laws of physics!"

I also found the E10 fuel to run rougher, and possibly cause cold temperature mis-fire. It also sounds more gratey under heavy acceleration.

E5 (really E2.5 at the time I used it) was an improvement, but it still hit fuel economy.

To summarize:

Fuel with zero ethanol is the best. 95 or 98 octane works very well, and the car returns best MPG.

E5 (E2.5) sees about a 5% hit to fuel economy. So 66 instead of 70 MPG.

E10 sees around a 15% hit to fuel economy, because E10 is the full 10% ethanol, and compared to E5 (2.5%) is an increase of 7.5% ethanol. The resulting loss of power due to the ethanol causes the ECU to put in even more fuel and maybe even change its timing, causing a significant loss of fuel economy. I estimate this hit to be around 15% from what the car can achieve on zero ethanol fuel (so 70 MPG becomes 60 MPG).

In terms of supermarket fuel, I use Tesco Premium E5 99 octane, and find it to be fine. I ran my last car on this for years without any problems. Texaco E5 Premium also seems to be fine.

As for the price difference between E5 premium and E10 standard, the difference isn't worth worrying about. Go with the best fuel you can.

The difference between 145 p/L and 150 p/L over 35 L tank, is £1.75 (or approx. 2%). I'm sure you can cost yourself more than that if you drive hard and fast everywhere. The fuel savings from increased MPG however, more than offset this price difference, so long-term you save.

[MikeSh]

38 minutes ago, YarisHybrid2016 said:

E10 sees around a 15% hit to fuel economy, because E10 is the full 10% ethanol,

If the ethanol had 0 calorific value then surely you'd see a 10% reduction in economy. So as ethanol has some value a 15% loss seems to be a bit of a stretch.

My MK3 shows significant variation in mpg over the year, and some variation between the 2 years I've had it, all on supermarket fuel. It seems to run just fine.

I honestly think people are falling for the hype about 'better' fuels rather than the one their car has been designed to use, and ultimately (sorry BP) are just giving money to big oil.

If it makes you feel better, and you can afford it, then fine. But please don't produce vague data on your single experience with one car as a reason for everyone to avoid cheaper fuel. Anecdotal evidence is the stuff of social media. (I stubbed my toe the other day resulting in a nasty bruise. My partner offered me some Arnica cream which I used, and after a few days the bruising has mostly gone. I could claim it's a miracle cure but I honestly have no idea if the cream helped or not. Cooking oil might have been as effective. Or nothing.)

[Corollanutter]

Personally I have found no significant difference in performance or economy between E5 and E10 in my Corolla 1.8.  Around 63 mpg in the summer and 57 mpg in the winter. But let’s face it, unlike the GR Yaris,  it’s hardly a high performance car! I can imagine that a car that squeezes every bit of performance out of its engine may well highlight some differences. However maybe I just drive gently - or maybe I’m not well enough attuned to notice the difference. Let’s face it, the economy of Hybrids varies significantly with the season and the journey type, so only very long term testing (or laboratory testing) would see an absolute like for like comparison. 

[YarisHybrid2016]

6 hours ago, MikeSh said:

If the ethanol had 0 calorific value then surely you'd see a 10% reduction in economy. So as ethanol has some value a 15% loss seems to be a bit of a stretch.

My MK3 shows significant variation in mpg over the year, and some variation between the 2 years I've had it, all on supermarket fuel. It seems to run just fine.

I honestly think people are falling for the hype about 'better' fuels rather than the one their car has been designed to use, and ultimately (sorry BP) are just giving money to big oil.

If it makes you feel better, and you can afford it, then fine. But please don't produce vague data on your single experience with one car as a reason for everyone to avoid cheaper fuel. Anecdotal evidence is the stuff of social media. (I stubbed my toe the other day resulting in a nasty bruise. My partner offered me some Arnica cream which I used, and after a few days the bruising has mostly gone. I could claim it's a miracle cure but I honestly have no idea if the cream helped or not. Cooking oil might have been as effective. Or nothing.)

Fair points.

I didn't just put one tank through it. I drove for a while (months) on E10, and noticed the reduction in range between fill-ups. That is when I went back to the E5 fuel (and confirmed the difference in range over months). I'm aware of the difference in MPG between summer/winter.

If E10 was as benign as you're trying to suggest it is however, then cars wouldn't need to be specially adapted to run it. The loss of power/fuel economy isn't linear with the concentration of ethanol, as ethonal burns differently to petrol as well as having lower calorific value (approximately 30% that of petrol), which further contributes to the loss of performance that the ECU compensates for by using more fuel.

[Eddiefh]

E10 is upto 10% , most tests I’ve seen are 5% - 7.5 % 

[YarisHybrid2016]

28 minutes ago, Eddiefh said:

E10 is upto 10% , most tests I’ve seen are 5% - 7.5 % 

Interesting. In that case, it's worse than expected. From what I read, Tesco E10 was 10%, but their E5 was 2.5%. Other outlets may be different.

I think sometime soon (if not already) E5 must be 5% regardless, and I presume the same is true for E10 (10%).

[FROSTYBALLS]

7 hours ago, MikeSh said:

rather than the one their car has been designed to use,

Toyota only state the minimum octane level as their fuel requirement - '95 or higher'. The majority of their engines (with a couple of exceptions) produced for the European market since January 1998 are E10 compatible.

[anchorman]

Where these fuels really score is they are dosed with detergents which really do have an effect on keeping the fuel and exhaust clean.  I only ever use it (read the small print on the photo).   I did try Tesco Millennium for a couple of tanks but it sounded harsh compared to branded but that is subjective.  

[jthspace]

2 hours ago, YarisHybrid2016 said:

Interesting. In that case, it's worse than expected. From what I read, Tesco E10 was 10%, but their E5 was 2.5%. Other outlets may be different.

I think sometime soon (if not already) E5 must be 5% regardless, and I presume the same is true for E10 (10%).

Esso is 0% in E5 in most of the country, check their website.  I thought the 5% and 10% were max amounts, not minimal?  

My MX5 ND will regularly give me 48/49 MPG on E5 but only 39/44 MPG on E10. Seems to vary on E10 based on supermarket vs brand. 

[MikeSh]

4 hours ago, YarisHybrid2016 said:

ECU compensates for by using more fuel.

But you are infering that 10% ethanol produces a 15% loss of economy. That would mean that adding that ethanol resulted in burning 5% more of the fossil component.

I think someone would have noticed that during the many years of science and engineering behind (less un)sustainable fuels.

 

3 hours ago, YarisHybrid2016 said:

From what I read, Tesco E10 was 10%

As others say, these are maximums. All these fuels are produced by a limited number of refineries, here and abroad, so the exact mix will vary a bit. Remember the big silicon nightmare in 2007 - that was fuel imported from Europe and mainly distributed in the south and east, so most other parts of the country had 'different' fuel.

[TonyHSD]

+1 for the premium fuel with lower ethanol content vs standard petrol E10. 
Not always but most of the times even if your car isn’t designed to run on premium fuel, using a premium fuels has benefits and it is wrong to think it’s just moneys spent on nothing. 
It is actually more important to find the best fuel possible either regular or premium and stick with it because no two garages sells exactly the same quality fuel even if they belong to the same brand, company, or area. 
I had the worst imaginable experience with premium petrol back in 2017 , the engine almost went burst, God knows what was in their tanks but the engine could had continued to run for few seconds after ignition key been switched off forcing me to engage gear and release clutch to choke it off ., when running was like an old tractor and there was almost no power at all. 
I saved the car and thought myself never premium petrol again. 
Then we had the new standard e10 , immediately noticed difference in performance mostly, engine noise and the efficiency, not as much as op says but roughly about 3-5mpg., I do a serious drives and use around 100ltrs a week. Tesco e5 99 is my preferred choice as best ratio value/quality/ efficiency/performance and availability locally. Not all Tesco garages though fuel been ok. , some different places when fill up the car feels like is running on e10. From all e10 s anywhere and from all other garages previous 95 e5 standard the best ever fuel for me was from local BP , always highest mpg, highest range after filled up and lowest engine noises.
No scientific proof, just my personal thoughts and experiences. 

[MikeSh]

43 minutes ago, TonyHSD said:

back in 2017 , the engine almost went burst, God knows what was in their tanks but the engine could had continued to run for few seconds after ignition key been switched off forcing me to engage gear and release clutch to choke it off 

I don't understand that. Was this a carburettor engine? Seems unlikely at that time. 'Dieseling' wasn't uncommon with those as fuel is ingested as long as the engine is turning. But fuel injected cars normally kill the fuel flow when the ignition is turned off, so it shouldn't be possible to run on unless there is a fault, like a leaking injector.

[TonyHSD]

7 minutes ago, MikeSh said:

I don't understand that. Was this a carburettor engine? Seems unlikely at that time. 'Dieseling' wasn't uncommon with those as fuel is ingested as long as the engine is turning. But fuel injected cars normally kill the fuel flow when the ignition is turned off, so it shouldn't be possible to run on unless there is a fault, like a leaking injector.

Hi, 

no carburettor, just port injection 1.6 petrol engine from 2008 very similar to any other engines from that era, all Injectors clean, everything in perfect condition. Only difference was this particular fuel. After the next refill at other place no issues whatsoever. 👍

[MikeSh]

That's very strange. If it was single point injection I could just about believe there might be enough fuel left in the manifold to get a couple of kicks, but that would be stretching it with port injection. (Unless it was continuous and not pulsed - did anyone do that for port injection?)

[anchorman]

They could run in a fashion on crankcase vapours if there was enough glowing carbon to ignite it.  

[Serban]

Interesting, I have seen no difference in MPG so far E5 or E10. But I didn't measure accurately either, I just looked at my dashboard here and there and I didn't see drops all of a sudden or that my acceleration to suffer, but I've also got a yaris mk4 so idk.

[Serban]

I've literally filled up my tank with E5, perhaps next time I try the tesco premium? Thing is, how would I notice the difference unless I'm looking at it with microscope lol. I can keep track for a couple of trips for fun I suppose if anyone could tell me what to look for 🙂

[TonyHSD]

Just now, Serban said:

I've literally filled up my tank with E5, perhaps next time I try the tesco premium? Thing is, how would I notice the difference unless I'm looking at it with microscope lol. I can keep track for a couple of trips for fun I suppose if anyone could tell me what to look for 🙂

Well, the first and most obvious difference is engine noise , then is the throttle response and then the acceleration, at the end comes the fuel consumption. The colder the weather is the larger the margin will be between e5 and e10. In my case during winter bhp to 5mpg in favour to e5 and during summer time almost no difference or up to 3mpg, but there had been cases that I had achieved actually a better efficiency on e10 bp refill during hot summer days. It is always a different case in different situations, uses. Try and see what works best for you and from which garage you like the most how the car drives and stick with it is my only suggestion. 👍
 

[Cyker]

It's likely there are other factors at work.

Firstly, ethanol has roughly a third less energy than petrol, so if you could run your car on E100 your MPG would be a third less (e.g. if you had a 99mpg car, you'd get 66mpg).

So with E10, all things being equal, would have a 3% mpg reduction.

In reality, it's a lot more complicated - E10 doesn't necessarily have 10% ethanol so the drop'd be less.

Also, E5, although it has less ethanol, usually has a lot more other stuff - cleaning agents, octane boosters etc.  etc.; These do not contribute to combustion and so will lower mpg too.

All things being equal, the difference between the two should be pretty marginal.

That's just from an energy point of view tho' - The higher octane rating of E5 means engines that can change their ignition timing and/or run at higher compression ratios, esp. turbos and our hybrids (With their crazy 14:1 ratios!  ) have the potential to extract more energy, but it's so variable it'd be hard to say either way...

 

On a slight tangent, I put in 26L of Texaco super 150-180 miles ago - So far my mpg has tanked: I was getting low-80's but I'm currently getting mid-70's. Do I think it's the fuel? Possibly, but more likely it's the drop in temperature we've had recently - I don't know about the rest of you but my Mk4 seems very sensitive to temperature.

 

[Jimota]

I’m no expert and can’t give any meaningful scientific information on the pros and cons of E10 and E5 fuels.  All I know, and I have taken account of temperature changes, my car definitely runs smoother, quieter and gives better mpg since changing to E5 fuel.

[FROSTYBALLS]

For a number of years, and before the introduction of E10, I've always filled up with super unleaded before going for a long run on the motorway. Cars seem to run better - never been bothered about whether fuel consumption better.

Topped up today with BP Ultimate (Momentum already  in tank) prior to going to Honley in Yorkshire on Friday 15/9, from there to Rothbury, Northumberland a week later, and back to Birmingham Saturday 7/10.

[YarisHybrid2016]

4 hours ago, Cyker said:

Possibly, but more likely it's the drop in temperature we've had recently - I don't know about the rest of you but my Mk4 seems very sensitive to temperature.

Too early for me to comment. I'd expect "a" drop, but I couldn't say how much.

I could analyze our Cross though...I always fill it up at the same place all the time, and my wife keeps detailed logs of milage at every fill for work ("sustainability") so we actually have excellent records for that.

[Cyker]

I've also noticed the engine runs 'smoother' on the E5 than on E10, broadly speaking anyway! It does vary, with Shell V-Power having made the least difference and Esso Synergy or whatever the heck it's called making the most noticeable smoothening (I'd be curious if it still does, as the big draw of Esso's super E5 is it had no E in it, but that is coming to and end this month alas!  )

Economy differences have been too small to notice - Differences caused by e.g. ambient temp and tyre pressures have had a much bigger effect and masked any the fuel may have made.

[Jimota]

On 9/14/2023 at 12:43 AM, YarisHybrid2016 said:

Too early for me to comment. I'd expect "a" drop, but I couldn't say how much.

I could analyze our Cross though...I always fill it up at the same place all the time, and my wife keeps detailed logs of milage at every fill for work ("sustainability") so we actually have excellent records for that.

Wish my wife would do the same.  She has this uncanny knack of handing the keys over to me when the tank is nearly empty.  Come to think of it, I really can’t remember the last time she put fuel in the tank.

[anchorman]

15 minutes ago, Jimota said:

Wish my wife would do the same.  She has this uncanny knack of handing the keys over to me when the tank is nearly empty.  Come to think of it, I really can’t remember the last time she put fuel in the tank.

That’s what you’re there for Jim 😉