Supermarket fuel, false economy..?

[wafter]

When I had "nice" cars they always used to get branded fuel, while my late mechanic father always warned me off supermarket fuel.

Since I've been driving less-nice cars and money has been an issue I've been mostly filling up at the supermarket. I keep a log of fuel economy and long-term the car averages around 45mpg, with a low of maybe 42-43mpg and a high of maybe 47-48mpg on one tank under normal use. I've touched 52mpg from a tank on a few long, sedate 50mph-all-the-way trips but this isn't the norm.

Recently I had cause to fill up with Esso as there was no alternative and got a little over 52mpg from that tank under normal conditions. Today I filled up again, and the last tank (Shell) managed just over 50.5mpg - the car having had the occasional thrashing during that period.

So... based on this relatively small sample it appears that branded fuel is giving me in the region of 10% better fuel economy.

In addition it seems that the difference to the cot of branded fuel decreasing while in some cases it seems that the supermarkets have actually been the most expensive. Today I filled up with Shell at 172.8p/l while it appears that the local Sainsbury's is charging 169.9p/l; around 2% less give or take.

Has anyone else noticed similar discrepancies in fuel economy?

Needless to say I'll not be filling up at the supermarkets any more..

 

[MichaelW2]

The answer from various car websites is yes/no.
This seems to be the kind of topic Top Gear could cover as a useful Public Information Service. Angela Rippon would have pounced on it like a voracious cougar back in the day.

 

[wafter]

The answer from various car websites is yes/no.
This seems to be the kind of topic Top Gear could cover as a useful Public Information Service. Angela Rippon would have pounced on it like a voracious cougar back in the day.

lol - I did do a bit of reading up and something I'd not considered was the potential variability in quality of supermarket fuel, as they probably just buy it from whichever source is cheaper.. so that's got to muddy the waters.

 

[gbb]

In my days of foreign travel for work, i used to get ferried to and from airports by a guy who had a 5 series BMW estate.
This was his business and drove a lot of miles for lots of customers. He was also very fastidious about mileages, costs etc etc and he was absolutely adamant he wouldnt use supermarket fuel because the times he did, his fuel economy dropped off.

TBF, i have no idea if there's anything in it, you hear opinions either way. I remember filling up a while ago at a Morrisons and for the next week got bad fuel economy....yet other times, it's made no appreciable difference. Wind, uphill routes, weather, humidity, there's so many variables, who knows.
I use to be averse to supermarket fuel....i do use it and can't say it makes that much difference (that i can quantify)
Same with E5, i used that for a spell, not specifically for economy but for the good of the engine / fuel system...again,, it was difficult to see it made much, if any difference to fuel economy.

 

[Scottish Scrutineer]

I must admit that I've been tying to avoid using supermarket fuel over the last few years. I notice that there is generally reduced fuel consumption when using mainstream fuels as opposed to supermarket. Even though in central Scotland, almost all fuel comes out of Grangemouth, the additives that go into the tanker at loading differs.

 

[cougie uk]

A military pal of mine (and they use a lot of fuel) had done lots of training on stuff like this and he told me that supermarket fuel wasn't as good as the pricier branded stuff.
I'm sure the AA or Which could do proper tests and give us the best per mile but I guess prices change all the time so it's instantly out of date.

 

[Baldy]

I used to be a tanker driver, it all comes out of the same pipe.

 

[Cycleops]

Angela Rippon would have pounced on it like a voracious cougar back in the day.

Agreed, but she's a bit old at 77 to be a cougar today though.

 

[figbat]

You need a much more scientific study to determine what improvement, if any, you are seeing. 10% in the world of fuel economy savings is HUGE - car makers will have your arm off for a 1% improvement. Fuel economy is notoriously tricky to evaluate under anything but the cleanest scientific conditions - there are myriad factors that impact it such as weather, traffic, topography, tyre pressure, wheel alignment, tyre condition, vehicle load, accessory use, barometric pressure and - biggest of all - the driver. No matter how consistent you think you are driving, you are not. In fuel and oil testing laboratories all of these variables are eliminated and a robot does the driving and improvements in fractions of a % are a good result.

That said, I see no reason why a 'better' fuel shouldn't give you some benefits, which can be incremental over time as fuel systems get cleaned up, injectors get more efficient etc.

I used to be a tanker driver, it all comes out of the same pipe.

The base fuel does, yes, but the additives that differentiate one supplier's fuel from another are dosed during loading, so fuels do differ between suppliers and it's the additives that make the difference.

 

[Jody]

You need a much more scientific study to determine what improvement, if any, you are seeing. 10% in the world of fuel economy savings is HUGE - car makers will have your arm off for a 1% improvement. Fuel economy is notoriously tricky to evaluate under anything but the cleanest scientific conditions - there are myriad factors that impact it such as weather, traffic, topography, tyre pressure, wheel alignment, tyre condition, vehicle load, accessory use, barometric pressure and - biggest of all - the driver. No matter how consistent you think you are driving, you are not. In fuel and oil testing laboratories all of these variables are eliminated and a robot does the driving and improvements in fractions of a % are a good result.

Good summary

You're unlikely to get any real discernible difference in fuels unless going 97-99 with a performance engine.

 

[Deleted member 26715]

Agreed, but she's a bit old at 77 to be a cougar today though.

I'll see your Angela Ripon at 77 & raise you a Jane Fonda at 84

 

[ClichéGuevara]

Just to throw another spanner in the mix, some of the 'cleaner' fuels can also be worse for the engine long term. Shell a few years ago being one more public example.

There's also a tolerance on the measurement system, that some companies exploit more than others, so not all gallons are equal.

One reasonable test is to pop some of your fuel into a petrol lighter, and see how it burns. Some will give a nice blue flame, others will be sooty and yellow.

You can have a mix of one or more of these, and other factors, such as the temperature when you fill up, and the moisture content and temperature of the air when you're driving.

I guess the wisest thing is to mix where you get the fuel from.

 

[BoldonLad]

I used to be a tanker driver, it all comes out of the same pipe.

This was always my understanding. I have invariably filled up at cheapest place, both here in UK, and in mainland Europe, be that supermarket or "Jet" type Garage. Never noticed any different in performance or consumption, nor, any effect on engine life. That is with petrol and diesel vehicles.

 

[Badger_Boom]

This was always my understanding. I have invariably filled up at cheapest place, both here in UK, and in mainland Europe, be that supermarket or "Jet" type Garage. Never noticed any different in performance or consumption, nor, any effect on engine life. That is with petrol and diesel vehicles.

Same here.

lol - I did do a bit of reading up and something I'd not considered was the potential variability in quality of supermarket fuel, as they probably just buy it from whichever source is cheaper.. so that's got to muddy the waters.

Since it all comes form UK refineries according a tanker drivers who deliver the stuff - apart from specific types and quantities of additives it's unlikley to be of 'poorer quality' in general terms.

 

[fossyant]

I know Super gives me 10% better fuel efficiency than E10 on a 'run' - I'll get 44 mpg over 70 miles on super, or just 40 mpg on E10,. Both still supermarket fuel.