SWMBO'd topped the car up for me before we took off for a long weekend. Shock at her paying 149.9 per litre. Standard round here is 136.9 for supermarket best. An even greater shock when the fuel consumption figures came in. A regular trip across North Wales and round the hills brings in between 55.00 and 63 mpg. We have just finished the trip on 43.4 mpg!!!

The loading was nothing different and the driving similar. No greater volume of traffic either.

I really disappointed and will certainly never make the same mistake again, simply can't afford it at those figures.

Pity as the weekend has been great, just need to wash the camping/walking kit...

£149.9!!!!!!!!! Even with all the alleged benefits of these superfuels, that's just ridiculous. I match your usual figures easily with ordinary Shell. Same price as the supermarkets round here. Mind you, even ordinary BP diesel was £1.43 at a garage I passed yesterday.

As a matter of interest I haven't used Ultimate for years, since I used it on a 51 plated IDI 1.9 Berlingo, and was confronted with a rough running bag of nails quite unlike its normal smooth self. However, I have occasionally used Total Excillium on a 2 litre Seat and found the MPG figure to be exactly the same and the price not as high as Shell V Power or BP Ultimate.

I haven't used Ultimate for years, since I used it on a 51 plated IDI 1.9 Berlingo, and was confronted with a rough running bag of nails quite unlike its normal smooth self.

Interesting. Ultimate had exactly the same effect on my X plated 1.9 Berlingo - which is why I have not tried it in my Roomy

We have just finished the trip on 43.4 mpg!!!

Just finishing a tank of 130.7p/litre Asda petrol in the 1.2 DSG and the trip computer is reading 44.8 mpg with 500 miles from the full tank easily achievable

This is very interesting, as I've been reading a thread over on the Yeti area and a lot of folks there swear that they get improved mpg with the dear stuff. Maybe its the type of engine we have that doesn't get the same advantage. Must say I've never found any better performance or consumption with any of my diesels on premium fuels. Tuned petrol cars are different though, I do notice a difference on my other car.

I really am struggling with the fuel consumption figures. Run to and from work usually shows 58mpg, managed 44 mpg!! So annoyed that I have topped up with the local supermarket in the (vain) hope of diluting the stuff already there.

Now I know why it was called BP Ultimate!

I am planning a long run this weekend to get the tank emptied and refilled with some proper juice...

Has anyone out there any reasoned explanation as to why the engine should be so badly affected by a change of fuel supplier? I presume that all fuels have to meet certain requirements?

I have heard some people report that you need to run 2 tankfulls through before you get the desired effect, but that's never worked on a diesel for me. I am baffled as to why your consumption has suffered, if you are driving the same way over a routine route.

Maybe the higher cetane levels have prompted the ecu to do a bit of a relearn and that has affected things?

2 Tank fulls! At the moment I am reluctant to go through that regime.

I note your comment regarding the ecu having to relearn and have picked up that comment on other forums. Wasted some of the works time today searching for comment on BP Ultimate and find that there are wide variations in experience: some very good, some very bad.

The 'Honest John' website carried a number of comments that lead me to understand that there will not be a significant increase in mpg: certainly the ecu relearning may have improved the figures over time but not enough to justify the increased price per litre.

On a separate topic, some of the 'Honest John' responses also comment on reduced engine noise/improved winter starting/smoother power delivery. I really didn't notice any difference, there again, I wasn't expecting it either. Again, maybe a longer (less shocked) test would reveal those benefits.

I might try and do a 2 tank test on Ultimate or similar one day, but I tend to use the Total garage down the road for the majority of my fuel, as its convenient and you don't get hordes of people holding you up with shopping for stuff.I think they do a premium diesel, certainly do an Excellium petrol ( gotta love those names lol ). The petrol one actually does work on my other car.

I have an idea that most oil companies use a slightly different version of diesel fuel in the winter to help stop waxing, winter diesel if you like. Its just at the ordinary pump though.