Is diesel "All the same"?

Dusty_Vinyl

all diesel is made to the EN590 standard, as with any standard there are certain tolerances which exist... I guess no two batches would ever be the same, but surely that applies to the route also, even with a regular journey which simply involves taking the kids to school will vary from day to day as there are other fuel consumption factors including time spent in traffic and rev/gear ratio.... the best way to improve your fuel efficiency is make sure your tyre pressures are correct (too low and it causes drag too high and you'll get premature tyre wear) also empty out any junk you might hve in your boot as the extra weight = extra duty for the engine = extra fuel.

AdrianHi

Dusty_Vinyl wrote: »

all diesel is made to the EN590 standard, as with any standard there are certain tolerances which exist... I guess no two batches would ever be the same, but surely that applies to the route also, even with a regular journey which simply involves taking the kids to school will vary from day to day as there are other fuel consumption factors including time spent in traffic and rev/gear ratio.... the best way to improve your fuel efficiency is make sure your tyre pressures are correct (too low and it causes drag too high and you'll get premature tyre wear) also empty out any junk you might hve in your boot as the extra weight = extra duty for the engine = extra fuel.

Other tests have shown low tyre pressures to actually have minimal affect on fuel used and you need to remove a lot of weight to get a measurable difference. Tyre pressures are more of a safety issue, so it is essential to correct them regularly (say every 2 to 4 weeks).
So I disagree with "the best way".
Using a fuel improving additive or a premium fuel according to my measurements is the best way to improve MPG given consistent weather, driving routes and traffic congestion levels.

Dusty_Vinyl

I seen a report on fith gear where they mesaured the performance of high octane fuels with a centane index greater than 95 (which is typical of BS:EN228 fuel) it showed that the increase on fuel economy was directly proportional to the increase in centane, however the increase in price was only offset my an increase in economy on petrol cars exceeding 2000cc and even more so on performance models.

so in response to your quote, yes premium high octane fuel like tesco premium 99 centane and Shell optimax 98 centane will give increased fuel economy but the £££ saving in the difference of £/litre premium only surpasses the increase in fuel cost on
larger engines and those with sportier performance.

the M3 I drive advises me to increase the tyre pressure in the rear for long journeys if I am carrying rear seat passengers or luggage exceeding 130kg ... you can check this on the sticker in the driverside door well next time you come accross one.

AdrianHi

Dusty_Vinyl wrote: »

I seen a report on fith gear where they mesaured the performance of high octane fuels with a centane index greater than 95 (which is typical of BS:EN228 fuel) it showed that the increase on fuel economy was directly proportional to the increase in centane, however the increase in price was only offset my an increase in economy on petrol cars exceeding 2000cc and even more so on performance models.

so in response to your quote, yes premium high octane fuel like tesco premium 99 centane and Shell optimax 98 centane will give increased fuel economy but the £££ saving in the difference of £/litre premium only surpasses the increase in fuel cost on
larger engines and those with sportier performance.

the M3 I drive advises me to increase the tyre pressure in the rear for long journeys if I am carrying rear seat passengers or luggage exceeding 130kg ... you can check this on the sticker in the driverside door well next time you come accross one.

We don't really talk about Cetane ratings in relation to petrol.
Octane rating of petrol (RON) is a measure of it's resistance to pre-ignition / pinking / dieseling. More resistance allows earlier ignition (spark) for a longer burn which can give rise to better fuel consumption and performance in an engine that can take advantage of the higher grade.
Cetane rating of Diesel is a measure of how well the fuel burns, where the EN590 specification defines a lower limit of 51 (in addition to many other parameters), no maximum. So any Cetane 51+ diesel fuel complies with EN590.

Dusty_Vinyl

OK, so perhaps I used the term 'centane' when I should have used the term 'octane', irrespective of that minor indescretion, I think my point remains valid.

Did you read Martins Lweis' article here which co-incidentally backs up everything I've said: http://www.moneysavingexpert.com/travel/cheaper-fuel ?

AdrianHi

Dusty_Vinyl wrote: »

OK, so perhaps I used the term 'centane' when I should have used the term 'octane', irrespective of that minor indescretion, I think my point remains valid.

Did you read Martins Lweis' article here which co-incidentally backs up everything I've said: http://www.moneysavingexpert.com/travel/cheaper-fuel ?

I think we are in agreement here.
Regarding "Step 3" on fuel grade. Most modern petrol cars will take 91 to 98 RON and higher, but higher than this is of no benefit. Standard unleaded is 95. Tesco's 99 RON is good value. Those "super" 102 RON fuels are indeed pointless unless you have a car tuned or re-tuned to take advanatage of it - but these are so expensive it would never be money saving