Supermarket Petrol

[Carltona123]

Hey everyone.

Filled up last week at Sainsbury's because somebody gave me a coupon. Now I know the weather's gone colder but I've noticed an immediate drop in fuel economy.

Anyone else had this experience?

Apologies if we've been here before.

[GreenJuice]

Yes it's typical and to be expected. More fuel needs to be burnt to raise the engine and cabin to desired temperatures.

[Mistermena]

Not sure about the quality of that petrol. But I know the Tesco's 99Ron is really good as its made by a very good company thats involved in motor sports. The guys off pistonheads go mad for the stuff. The mpg will suffer now because the density of the cold air...

[timberwolf]

I filled up at the weekend with Sainsbury's and my mpg for the last three months was 49.26 mpg but the last tank was Shell. It's not the lowest I've had, but I had expected it to be a bit higher because we've apparently had higher than average seasonal temperatures until recently.

[Chris Dance]

I always use super market fuels. Tescos mostly. At the moment I am getting about 67MPG.on a Gen 3.

[Carltona123]

Mmmm - it has got cold, but the second I put that Sainsbury's stuff in my mpg went south. Having said that, 50 mpg for a 3 mile commute is hardly cause for complaint... Part of the problem is that I was spoiled in the Summer - my first with a Prius. Roll on the Spring!

[Grumpy Cabbie]

I know in America some States mix upto 10% ethanol into the petrol and this does reduce fuel consumption slightly (less energy in ethanol).

In the UK I know that the EU insists a certain amount of bio ethanol is mixed in ours but presently this is about 2.5% to 5% max, but I'm sure I've read that upto 10% can be legally added (and not damage engines or invalidate warranties) and that SOME smaller refineries add this. Could these be the refineries that produce petrol for some super markets in some areas and hence users of this fuel are finding lower mpg's?

Saying that, the cold weather does make a significant reduction in mpg's on the Prius.

[Carltona123]

Interesting about the ethanol - supermarkets trying everyone trick in the book to increase their margins so who knows what they'd try.

I tried some of that E85 in the Summer in the USA - fuel consumption absolutely plummeted.

[kithmo]

I had 2 tankfuls of Sainsbury's unleaded in June and the mpg went from 62 on the previous tank of Shell to 58 on Sainsbury's then back up to 60 on the second tank of Sainsbury's. So a definite drop, but not significantly different to a change in weather or driving style.

[Mistermena]

Anyone use Tesco's 99Ron Momentum petrol? What you think of it?

[Opifex]

Interesting about the ethanol - supermarkets trying everyone trick in the book to increase their margins so who knows what they'd try.

I tried some of that E85 in the Summer in the USA - fuel consumption absolutely plummeted.

E85 is 85% ethanol and the engine tuning needs to be altered to use it. A few years ago Saab produced a car designed to use it but the idea doesn't seem to have caught on and I haven't heard any more about it in the UK since then.

According to the DirectGov website the maximum ethanol that can be added at present is 5% to petrol and 7% to diesel.

There was a government consultation last year about whether E10 (10% ethanol) should be introduced into UK but I can't find anything about its conclusions. The E10 pumps in France are clearly marked, and I assume they will be in UK when it arrives. I've only tried it twice - the first time the consumption dropped dramatically, second time the drop was not as great but was still noticeable. Both times I was on a long motorway trip so the change was definitely fuel related and not due to weather changes.

[Cyker]

Nooooo, if you added Ethanol to diesel you'd probably wreck the injectors!

It is not good stuff anyway (Its sole advantage is it raises octane ratings; In every other respect it's worse than normal petrol!) and slowly damages the injectors and pump parts even in unmodified petrol engines, but as it has almost no lubricating properties unlike biodiesel the effect on a modern CR diesel injector would be something like mixing water in the tank!

We derv people get biodiesel added instead which, unlike ethanol, doesn't slowly destroy unmodified engines :D

(Although it will degrade the organic rubber hoses and seals in old cars...!)

[Opifex]

I stand corrected.

The DirectGov site refers to biofuel and I'd assumed this meant ethanol. Looking on Wikipedia it seems that biodiesel is a mix of various plant and animal fats - it sounds more like a recipe for margarine. :)

[Joseph D]

I had exactly the same question as the OP, so rather than start a new thread, I thought I would reply to this one.

Yes, I filled up for the first time with Sainsbury's unleaded (Morecambe, Lancashire, if that makes a difference), drawn by the super-cheap price (£1.279) and have noticed an immediate drop in MPG from my normal late 50's to early 60's to now struggling to get above the early 50's.

I have used other "supermarket" fuel and have not found any perceivable difference outside of a normal margin of error, so I'm not worried about name brand fuel v's supermarket fuel. Over the last 16 tanks, I have used Shell, BP, Esso, Total Gleaner and Tesco and have not found a significant difference outside of a normal seasonal variation. But with this last tank of Sainsbury's Unleaded, the change in MPG was immediate and significantly noticeable.

In trying to find a reason to explain it, I got wondering whether there is a higher (bio-)ethanol content (closer to 10% than 5% maybe??) in Sainsbury's fuel (hence the cheaper price), but cannot find any information at all that relates to the make up of the Sainsburys' offerings.

Any one know what the percentage of ethanol is in Sainbury's fuels and whether this could be the reason for the sudden drop in MPG's that the OP and I noticed.

If not this, does anyone have any other theories?

[Grumpy Cabbie]

In trying to find a reason to explain it, I got wondering whether there is a higher (bio-)ethanol content (closer to 10% than 5% maybe??) in Sainsbury's fuel (hence the cheaper price), but cannot find any information at all that relates to the make up of the Sainsburys' offerings.

Any one know what the percentage of ethanol is in Sainbury's fuels and whether this could be the reason for the sudden drop in MPG's that the OP and I noticed.

If not this, does anyone have any other theories?

The ethanol content of unleaded petrol is to become 10% in 2013 whether you like it or not. It is already sold in France at this percentage as an option. I'm guessing that with 5 months to go, that supplier to your petrol station has already increased their ethanol content in anticipation of this new requirement? As ethanol is much cheaper to purchase I guess it makes sense for some refineries to introduce it earlier?

My question here would be what petrol is used by the manufacturers to produce their official fuel consumption ratings? I'm wondering if they're using 100% petrol giving the best mpg's, yet Joe Public is going to end up running on 5% or 10% ethanol with a reduced economy.

Ethanol is more prevalent in America, some States offering 15% as standard and the Prius is apparantly able to run satisfactorily on this, though will reduced economy. There are reports of some users using E85 (85% ethanol) mixed with small amounts of additional petrol giving approx 50% total ethanol content, though they are risking LONG TERM DAMAGE to their vehicle. Makes you wonder about our American friends sometimes. They have the Worlds cheapest petrol, they drive the worlds most economical family sized car and then try to eke out a few more pence savings running on a fuel not designed for their car! Must have family roots back to Yorkshire? :)

[Opifex]

Found this on the Directgov website:

Biofuels can be mixed with ordinary diesel or petrol and used in normal cars. Much of the diesel available in the UK, and some petrol, contains biofuel. Petrol contains up to a maximum of 5 per cent and diesel 7 per cent.

In France 10% ethanol pumps are clearly marked. I've used it twice and found the mpg dropped noticeably so now I avoid the stuff. Most petrol stations in France are still selling normal unleaded (marked SP95) but Shell seems to have gone over entirely to 10% ethanol (marked SP95-E10).

[johalareewi]

Add ethanol to unleaded = less fossil fuel used = lower mpg = have to use more fuel to go same distance = drivers buy more fuel = more revenue for the government. Green Agenda tick, Increased Revenue tick.

I hope that we will still have the choice of pure unleaded or 90% unleaded at the pump but I doubt it. Super unleaded anyone?

[timberwolf]

More people starving in the world as food production is diverted to fuel production, check.

[CO2SLAVE]

Anyone use Tesco's 99Ron Momentum petrol? What you think of it?

not tried this yet.... Has anyone else got experience to offer on the economy difference between super unleaded and regular ?

I reckon you would need to get about 6% better fuel economy to make it worthwhile at todays prices ( about 7p more per litre)

[valmiki]

I ran on Tesco 99RON for a couple of months, soon after buying my Prius in February. At my local Tesco's, 99RON is 5p more expensive than the regular stuff, and it was more out of habit from when I had my 5-series. In that car it did make a impact!

Once I switched to regular, didn't make much difference - but this could be down to driving conditions at that time of year, cold weather plays havoc with my mileage since my journeys tend to be shorter and around town mostly, so it's hard to be objective when comparing efficiency between fillups. I've also read somewhere (possibly Prius Chat) that premium unleaded doesn't really suit the Prius as it's not set up to take advantage of the higher RON. However, there are more lubricants in the premium fuels that may have some benefit over the longer term.

[Bibsy]

Only anecdotal, but my Gen2 is run almost exclusively on Tesco ordinary unleaded, and consistently gives me 62mpg (on the computer) in the summer. It's been at that figure for the last couple of months.

Fill before last I chucked in a tank of super momentum stuff, and the mpg was instantly worse - I got 58mpg on the screen for that tank, no difference at all in weather or journeys.

Filled last week with ordinary again and straight back to 62 mpg, again no significant change in weather or journey.

56-58 is more like the mid winter figure for me (with one hot hot July giving me a rather lovely 72 tankfull).

[Grumpy Cabbie]

I wonder if the reduced fuel economy was due to the very wet roads and colder temperatures we've been having? Wet roads mean more resistance on the tyres.

Alfternatively, it's interesting to see the comments on here about using 98RON Super Unleaded, whereas on the American forums they have figures to show that running on anything other than Regular Unleaded in a Prius is a waste. We don't even get Regular 92 RON here, our lowest being 95 Premium.

[ian rooke]

Hi I have tried running on unleaded and super unleaded and have had the fuel consumption improve about 4 to the gallon on super unleaded which is not enough to warrant running on super unleaded .

[kithmo]

I stand corrected.

The DirectGov site refers to biofuel and I'd assumed this meant ethanol. Looking on Wikipedia it seems that biodiesel is a mix of various plant and animal fats - it sounds more like a recipe for margarine.

I doubt that margarine has any sort of organic material in it. Leave an open tub in the garage for a couple of months and very little happens to it, whereas butter will go off.

[Cyker]

Ironically the petrol-ethanol blends work much better in high compression and turbo-charged petrol engines as the ethanol acts as an octane booster additive.

The Atkinson-cycle engines in HSDs are worse off as they are designed to extract maximum energy from the fuel, but ethanol contains much less energy than petrol. Judging from the way they work, I suspect the Atkinson engines get very little benefit from high-octane fuels above

If they used turbo-charged 1.0VVTi's it'd probably work better (Plus the weight saving would provide a large mpg boost; I really don't get why the HSDs have such large engines - The Yaris HSD's petrol engine is the biggest engine in the range!)