BP Diesel Ultra

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Originally Posted by vnx205

You may be right, but I still believe that the consistency with which you fill the tank is a bigger factor than many people realise...

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I know what you are saying, that's why I use a spreadsheet/ database arrangement and calculate the results. Over time trends show.

If you get outstanding fuel consumption and the next fill delivers rubbish you can just about guarantee the fill you used to calculate the first figures wasn't filled to the top.

I like to chart the results, showing an overall average and a last 10 fill average. It can often point to a developing problem before something more sinister manifests itself. If your consumption unexpectedly increases (the 10 fill average is climbing) its time to work out why.

At last! Someone who speaks the same language as I do! :p

As you say, long term averages are what matter. That minimises the problems that I have suggested may be the reason some people mistakenly believe that they have seen a difference in economy. Your idea of an average of the last ten fills should give you meaningful information.

It certainly means a lot more than the claim we hear so often that the previous tank gave x litres/100km and this one gave a different figure.

Where I live our diesel is imported by ship (from Singapore as I understand things). No matter where it comes from it leaves the port via a single underground fuel line connected to both the Shell and BP terminals. The diesel they are receiving is identical for both companies. Not sure if they actually add anything prior to trucking the stuff to local servos but you have got my curiosity going so I will ask around.