Optimax

[wilkoturbo]

Just put Optimax diesel in will I see any gains ????

[X5Sport]

I thought they did eye-sight laser work?  You sure you don't need to go to Specsavers.... :blink:  )

[Cannondale]

I put a take of the fancy Shell petrol in mine last week, it did about 25 miles more on the tank than normal petrol. Didnt feel any diffrent to drive

Richard...

[AW8]

It's actually branded Shell V-Power now & has been for some while. I run both the V8 X5 & the Z3 on V-Power albeit I get annoyed at the significant changes in price difference between V-Power & Shell Fuel-Save.

If its mpg gain you seek I would also try the Fuel-Save & see how that works out.

I have read that if running on a particular fuel you need a few tanks before the engine edjusts to it in order to get best from same...........No idea if this is true as to me it's hearsay but no readson to disbelieve.

On a couple of tanks of V-Power all cars seesm to be running well & a little more responsive. I haven't done the maths though as tbh it is near impossible to see if there is any diference unless driving in identical conditions and comparing............e.g 20 degree outide temp, engine fully warmed, aircon off, cruise at 60mph in top gear,  straight level road for say 2 miles,  pressing recalculate on the OBD and noting the mpg figure - then replicating/comparing same for various fuels after running a few tanks of each 1st before the experiment.

Even then there are other variances such as how car is performing efficency wise based on sensors, plugs, filters, plugs tyre pressures, type of tyres not to mention outside factors such as, strong winds, surface water, air quality temp & mositure content/humidity. Peformance & mpg wise there will also be differences say when driving solo on 1/4 tank compared say driving the same car fully laden car with a full tank.

Finally I should mention that computers lie and the accuracy of mpg is only as good as the parameters settings being correct on OBD.

What do I do ? I currently run V-Power & when I remember to do so I check tyre pressures & scan car for fault codes. The Z3 seems to respond better to V-Power but then again that car with that engine & exhaust set up seems better at communicating minor fuel performance differences. Z3 doesnt even have OBD so tbh I don't try to calculate mpg with any degree of accurscy. It seems to do around 30 ish to the gallon & more if I drive Miss daisy on a run.

In honesty I reckon that any diferences are fairly insignificant when all other factors metioned plus & driving style/route/traffic flow etc are considered.

99% of folk fill up drive & arrive............that's it.

[graemeX5]

[quote="X5Sport"]
I thought they did eye-sight laser work?  You sure you don't need to go to Specsavers.... :blink:  )
[/quote]

When I viewed this what made me laugh even more was the advert for 20:20 laser eye surgery at bottom of page.

Oh yes the fuel mileage and performance on previous car Vxr with a turbo only used shell v power and car was more responsive, no better on fuel probably the way I drove it?

On the x5 I used normal shell unleaded and on a run about 23mpg on route to work this week, but round town 16-18 approx. I think I will try a tank on the x5 next time. On audit TT 3.2 using only shells v power and getting between 24 and 35 depending on use in town or on run.

However, the biggest differnce on both is remembering to use cruise control on both it definitely helps increase mpg

[X5Sport]

There was an exchange (mainly PM) about these 'super fuels' in the X6 40d with the surprising outcome that the car ran far worse than on normal diesel.  How the petrol versions perform may be different, but on the face of it I can see no advantage for V-power diesel in the latest version diesel engines. 

That of course then begs the question - so why don't they like running with it?  Tighter limits on the DDE engine maps for emission controls perhaps?  Anyone got a theory?

Richard

[shadrack]

i tried it in the past and couldnt tell the difference, as aw8 says above there are just so many factors i really cant see how it can work, there is also no such thing as cheap crap petrol/diesel in the uk, maybe its just a placebo in that people think they are going to get better mpg and inadvertantly drive slighty better and get a mariginal improvement in mpg? its like the michellin fuel save tyres there is son many 1000s of factors as aw8 says how can they ever prove a mpg increase or not, same as the user will never know what they would have achieved using standard petrol/diesel/tyres ::)

[X5Sport]

I use and am perfectly happy with supermarket fuel.......

[shadrack]

[quote="X5Sport"]
I use and am perfectly happy with supermarket fuel.......
[/quote]
+1