MPG different to the petrol garage you choose!

[chiz]

Is it just me or is it the case that when you are measuring your MPG, there is a difference between petrol manufacturers. I was getting different results each time I filled up with petrol. I thought that it was to do with the way that I was driving between each tank fill. Then I started measuring my diesel usage on my day to day car and I really do think that I am getting a difference between garages, especially supermarket and main fuel suppliers.

Or is it just me. What is the best fuel to price ratio? Has anybody else noticed.

[Mocki]

Can't speak for others, nor can I say if it's true for diesel or petrol, but it definitely differed between different brands with LPG

[The Bishop]

Can't speak for others, nor can I say if it's true for diesel or petrol, but it definitely differed between different brands with LPG

Is it the brands or the pressure in the pumps?

[Mocki]

Well some pumps definitely do deliver at a higher pressure, that's a fact...
However I consistently get better mpg on BP and jet LPG over morrisons or total.
She'll seems to vary depending on location.

[AdrianC]

Well some pumps definitely do deliver at a higher pressure, that's a fact...
However I consistently get better mpg on BP and jet LPG over morrisons or total.
She'll seems to vary depending on location.

Is it the actual consumption that's varying, or the range per tank? If you're putting less into each tankful, you'll get less far on the same economy. If the pressure or the pump design or the nozzle angle are different, then the cut-off'll happen at a different level in the tank. On LPG, there's probably even more variables as to why the cut-off 80% pressure'd be reached.

Doing any kind of consumption calculation based on individual tankfuls will always give wrong results - you've got to take an average over several tankfuls.

[Big-John]

Few years ago now, I decided to do a fuel check across our fleet of Coaches, we were using tank full to tank full and across all aspects of driving, when you took into consideration that each coach on average had a 250 gallon tank/tanks the results were pretty good, from our own yard supply the mpg was appalling, when using BP and paying forecourt prices it worked out cheaper, the test wasn't popular as it meant swapping drivers from their own coaches and different routes were used for the school coaches, ie we started sending them further afield, apart from one driver throwing a wobbly and leaving, and a few more breakdowns i managed to push the test to a year, the conclusion was that BP Diesel lasted longer right across the board, we could also track the drivers hardest on their coaches from brake wear/clutches etc, ok it was not popular but we got a better idea of what was going on.

[chiz]

You see this is very interesting because I have just been speaking to a guy who used to sell engine and petrol additives. He says you should never buy fuel from a supermarket. Their fuel has not all the detergents and lubricants that forecourt fuel has. He says that he thinks that you will always get better mpg on a brand fuel against the supermarkets.

[AdrianC]

You see this is very interesting because I have just been speaking to a guy who used to sell engine and petrol additives. He says you should never buy fuel from a supermarket. Their fuel has not all the detergents and lubricants that forecourt fuel has. He says that he thinks that you will always get better mpg on a brand fuel against the supermarkets.

The fuel sold in supermarkets is the same fuel from the same tanks at the same handful of regional distribution depots as any forecourt. The ONLY difference brand-to-brand is the small bucket of additives poured in to the tanker when it's filled.

There may be a difference where there's a small low-volume forecourt selling a tankerful per month, with inches of grit at the bottom of the tank, though...

[The Bishop]

I was listening to the radio today and they suggested that whilst the supermarkets have something like 1/3 of outlets they sell 2/3 of all petrol sold (my figures probably aren't right but you get the jist of it). Assuming the supermarkets are so dominant, if their fuel really was delivering less MPG surely the media would have latched on to it by now. Everyone likes to kick Tesco.

With all the regulation I would have thought that the "combustibility" of one gallon of a given grade of fuel had to be the same wherever it came from?

If not the case, perhaps you are onto the next big news story.

[chiz]

It must just be my driving style. I thought that I was onto something when I started to measure my car MPG as the journey I take is the same every day. But it must just be me.

I do have to agree with the Bishop in that all given petrol or diesel should be made to the same precise specification.

[Mocki]

Not sure about petrol or tractor oil,not used either since 2003 to speak of but supermarket LPG is not as good as branded.
I have data from over ten years of LPG use , not just a couple of tank fulls .

[California Dreamin]

I do have to agree with the Bishop in that all given petrol or diesel should be made to the same precise specification.

It is made to meet a specific standard, that standard has changed over the years to reflect the ever stringent emissions standards, however, as fuel (diesel & Petroleum) is a cocktail of ingredients, not all fuels are made equal and some are made more cheaply to just meet standards where as others exceed those standards often including other additives that improve various aspects of the fuel over and above that which is required.

Martin