in the past i’ve always every once in a while treated the car to a full(ish) tank of shell v-power as i thought it do the engine some good. we recently bought a new car (ford c-max) and as our last car did not give you a fuel range we never thought anything of it up until now….you see, the c-max tells you the fuel range so when i filled it up with a full tank of shell v-power i was shocked to see that the range on full only said 394 miles!
previously the range had said 487 miles on a tank of regular shell unleaded…this got me annoyed as last night i filled up again at the local sainsburys and this time it says 427 miles…
maybe its down to the engine computer assessing the amount of fuel compared to my style of driving i.e. gear change pattern etc or could it be that i may have gone to a dodgy shell garage that was palming off regular unleaded under the v-max label…but i presumed that v-max would give you improved economy and performance….or have i got it wrong?

Pretty sure the fuel doesn’t tell the range meter when you fill it up that it can go further. Plus its all based on your mileage before filling anyway. Mine often says 450-470 and then goes up to 520-530 by the time I get home.

Mine often says 450-470 and then goes up to 520-530 by the time I get home.

last nights fuel on a full tank said 427 by the time i had got home it said 424…2 mile drive up a hill….but i would have thought a more expensive and higher quality fuel would give better economy…performance-wise there doesnt seem to be much difference

The car has no idea what fuel you have put in. It is purely going on how much fuel is in the tank and previous driving style. Not sure if this works in a rolling manner (e.g. the avg fuel consumption over the last 500 miles or what).

In my car, it is quite normal for the range to say, for example, 100 miles when I start the car from cold but then I can be 30 miles down the road after some gentle driving and it still says 100 miles.

So, if you do a load of long motorway drives and then fill up, you are likely to be greeted with a higher range figure than if you do a load of short urban trips and sit in traffic a lot before filling up.

I’d ignore the range thing. It’s a very rough guide at best. If you want to get an idea of fuel economy/range you should do brim to brim calculations, resetting the trip odometer every time and noting the mileage down.

Oh, and I don’t think any mpg improvement seen by a ‘special’ fuel would be big enough to see, compared to the ‘noise’ in the results between different driving scenarios per tank of fuel.

So 2 miles of stressing the engine up a hill reduced your fuel consumption. Sounds about right. Take it for a cruise down the motorway and watch it go up. Or just not worry and stop wasting fuel on testing your range computer which is a rough estimate anyway.

The computer doesn’t know how good the fuel is in the tank, it just basis it’s calculations on what driving you are doing and your driving history.

***Insert generic facepalm picture here***

only reliable (and even then it has its limiations) is to brim your tank – drive it well down (more you use the less error is induced) and rebrim – note milage and litres to refill

anything else is a number out the sky.

fair enough…you may have a point there…its just that i would have expected something better from shell v-max considering its premium price…

oooh, these knickers are really chaffing my balls!! 😆

The range given when you fill it up will be based on fuel consumption figures since you last reset the trip meter. It has nothing to do with the type of fuel you’ve put in!

Sort of as above really. Did you fill up after either driving through town or was the engine cold (both of which would result in greater consumption and therefore lower range when you filled up.

Higher octane fuel does not produce more power BTW

I would have thought your fuel tank/car computer measure the volume of liquid in the tank and make a guestimate, don’t think it check the enthalpy* of the fuel you put in

*if thats the right word

oooh, these knickers are really chaffing my balls!!

That might affect your range from a full tank too. 😯

I only get better fuel economy out of V-Power on a motorway run, otherwise the better performance encourages you to accelerate more and therefore reduce the fuel economy, so ending up about the same as normal petrol…

As above. The range indicator (on my car at least) is ONLY based on the last 5-10 mins of driving and how much fuel there is.

If I drive around town then hit the motorway the range to empty increases.

If you are concerned about economy, then you need to fill a tank and reset the trip. Then next time you fill up, take the number of miles you’ve done and divide by the amount of fuel you’ve put in. That is the ONLY reliable method. Do it for different fuels to see the difference, but only if it’s the same driving route and conditions each time.

before the v-max fill up we had done a lot of urban driving with a few motorway trips…the furthest being manchester to crewe and back…but before last nights fill up we had driven from manchester to birmingham and back via wrexham so you may have a point.
it doesnt bother me really, but it bothered me enough to put it on STW, but anyway thanks for the info…i’ll just avoid shell fuel in the future 😀

Higher grade fules contin better additives which keep injectors cleaner than bog standard stuff. You can also get get a marginal increase in energy density in the fuel which can give a marginal increase in power. Octane ratings are are for the ability to resist engine knock. Most modern engines don’t need a higher octane rating. You maybas well use cheapo stuff and just bung a bottle of cleaner in once every couple of month. Taz…used to work in fuel formulations labs for very fast cars n ting

With v power and basic chav fuel, how do you actually know chav petrol hasnt been put in the v fuel tank tio make more of a profit for the owner.

Its not red coloured like some diesel you see in taxis.

Taz was that at Stanlow by any chance?

thanks taz…i should have bought a diesel instead then this could have been a DPF thread instead… 😛

With v power and basic chav fuel, how do you actually know chav petrol hasnt been put in the v fuel tank tio make more of a profit for the owner.

that’s what i initially thought as with a full tank of the stuff driving down to birmingham at a leisurely pace the fuel range did not increase as i expected….

Ah, if you bought a car with DPF then v-power would be a wise investment! Its saved me all sorts of bother with mine. Supermarket stuff makes it run like toilet.

Sometimes I find that a full tank says the range is 370 miles, but when I open the bonnet and speak nicely to the engine telling it that it was actually a more expensive fuel (as opposed to Asda’s cheapest), the range can go up to 371.
PS that only works on Japanese engines, German ones seem to be far less gullible

“i’ll just avoid shell fuel in the future “

Are you sure your qualified to be driving – how did you pass the numberplate reading part of your test ? ITS NOT THE SHELL FUEL ITS USER EXPECTATION ERROR

Its not red coloured like some diesel you see in taxis.

Agricultural red diesel? Wouldn’t it be illegal for the taxis to use it?

i’ll just avoid shell fuel in the future

Huh? How many miles per gallon did you actually get from the tank of Shell?
How many did you get from the tank of supermarket stuff before that?

That’s the only way to know. You could fill the tank with water, the car would think it was full and tell you “480 miles left” but you wouldn’t actually be able to travel that 480 miles would you?!

Thinking about it…..
If the fuel economy was based on the mpg of the previous tank of fuel then
1. You fill up with an unknown type of fuel (you know what it was, you just havent told us).
2.You empty the tank over 487 miles
3. You fill up with normal Shell. You look at the computer and it estimates you’ve got a range of 487 miles, seeing as that’s what you got from the last tank.*
4. the normal Shell actually isn’t very efficient and you empty the tank in 394 miles.
5. You fill up with Vpower and look at the computer again. It estimates you’ve got a range of 394 miles, seeing as that’s what you got from the last tank.
6. You decide that Vpower must be rubbish so when the tank is empty, after 427 miles (Better than what you got from the regular Shell) you put cheapo supermarket fuel in.
7. You look at the computer and it tells you that you’ve got a range of 427 miles, seeing as that’s what you got from the last tank.
8. You take this as proof that supermarket fuel gives better economy that Vpower. 😕

ITS NOT THE SHELL FUEL ITS USER EXPECTATION ERROR

at 12 pence per liter more than the standard stuff, id expect more from it considering the marketing blurb seems to suggest that too…
what’s the numberplate reading got to do with the supposed quality of fuel?

Sharkbait…just down the road from stanlow….

1. You fill up with an unknown type of fuel (you know what it was, you just havent told us).
2.You empty the tank over 487 miles

it was the same cheapo sainsburys stuff and was used up doing the school run and traveling to and from work…(urban driving)
i accept everything as Bails says as that is how it should work but given that the the 487 was achieved from the cheap stuff, i’m a bit stumped over this…

what i should have said was

i’ll just avoid THAT shell fuel garage in the future

Basically, when you look at the range immediately after filling up, what you’re seeing is the result of a calculation based on the economy of the PREVIOUS tank of fuel.

So if you use fuel X, then fill up with something posher and see a low range estimate, that’s because the previous tank was relatively uneconomical.

The only way to know what actually happened is to look at the mileage you did between fill ups.

And then of course a long motorway journey, or better traffic on the commute, or different weather/tyre pressure/stuff in the boot will all affect it too.

as long as your looking at your range computer your just getting fed complete bollox – doesnt matter what fuels in it.

Everyone else has already covered why the range indicator has no connection to the type of fuel in the tank but it’s also worth mentioning that you will only get increased range if your car is pretty modern and has very sophisticated engine management. As someone mentioned, there is no more energy in high octane fuels (there is actually fractionally less), the only reason they can possibly make a difference is because the greater knock resistance allows the car to run fractionally leaner (less fuel for any given amount of air taken in), and more importantly, it allows the timing to be advanced further without causing premature detonation, or “knock”. More advanced timing will produce a little more power with a little less fuel, so assuming you drive the same way as usual and therefore use the same amount of power, you use a little less fuel to do it. Very few cars are sophisticated enough to do this and no cars sample the fuel in the tank to know what fuel is in them.
There are also some detergents in V-power which help clear out injectors and such like but if your car is fairly new that probably won’t be making much odds.
On the how do you know it’s not the same petrol in both pumps thing, I’ve run tuned Imprezas in the past which were mapped for Super unleaded only and if you were forced to put in normal fuel the warning lights for excessive knock would be lit up like a Christmas tree if you tried to use any level of performance, so it’s definitely different stuff.

And then of course a long motorway journey, or better traffic on the commute, or different weather/tyre pressure/stuff in the boot will all affect it too.

i checked the tyre pressures on tuesday and found all 4 tyres were at 28psi…when the recommended minimum should have been 35 at the rear and 33 up front…

So a more appropriate thread would be “my tyres were way under pressure and my fuel economy got worse”… 😆

My old c-max only drank shell, not v-power I’m too poor, but the normal stuff. It stuttered and burped constantly on supermarket fuel so it was a no brainer.

My Hyundai doesn’t give a toss.

So a more appropriate thread would be “my tyres were way under pressure and my fuel economy got worse”…

probably true….given that i’ve only have the car for about 2 months…i presume the tyre pressures were done at the dealers….so much for them doing a comprehensive pre-sale check before giving the car to the buyer!! i think i’ll be having words with the sales rep at evans halshaw…not because of the fuel economy but the fact that under inflated tyres can be as dangerous especially when you’ve got kids in the back

when they have picked them selves up off the floor from laughing at you they will point out that in 2 months you should have checked your tires 8 times im sure…. weekly check if your reaaaallly that concerned.

in the past i’ve always << yada yada yada>>

Buy a Dender, and cease having to worry about such things*

* though you might start to worry why it is raining inside.

Erm…you having a laugh aren’t you? You should check your tyre pressure at least once a month…bloody nora do you expect the sales rep to make sure you’ve got a seat belt on as well. You do kinda have to take personal responsibility now n then you know 🙂

not really as i have already complained to them over the fact that there were fuses missing they should have checked for, the car wasnt valeted properly as they promised, they gave me the run around over certain warranty documents and mot certificates, and the fact that the car suddenly had gained an extra 75 miles on the clock between the time we paid the deposit and collected the car a week later…all these niggles are currently being looked into by their complaints team so why shouldnt i add this to the list? i’m not expecting to get anything from them over this but to point out that their level of customer care hasnt been good…maybe i was too gullible in trusting them when they assured me that everything will be fully inspected and the car will be “right” for when i pick it up

You do kinda have to take personal responsibility now n then you know

in my defence its the wife’s car and she drives it mostly…the only time i really drive it is if we go somewhere far or when i take it to the garage to feed it some fuel