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Well shit me sideways. Never knew that. Just looked it up in the manual and there is indeed a fuel connector control in the 5, looks to be drivers side footwell on the centre console at that flap in the bottom.

It says this is only the 4afe engine with cat that has it (a yank only engine?) and this is apparently for running American 91 Octane 'Fuelweiser' :laugh2:

Connect it together to run on all american super super low grade, pull the connectors apart for 95 grade or higher.

Of course this is where you say 'but mine was a 3SGE' and then I will be confused haha. Or wonder if this is a prefacelift manual, hmmm :think:

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I filled up 3 times with 99 octane petrol, mostly Shell but BP when I couldn't get Shell VPower.

Before this I just used Tesco or BP 95 or the cheapest available, and managed around 32-33mpg general normal driving, same trips or style of driving most of the time.

I reset or powered down my ECU after filling with 99 to let it re-learn and surprisingly managed 32-33mpg on average across all 3 tanks of fuel, I cant say I noticed the car drove any better or performance improved (don't drive it hard so difficult to tell).

Went back to Tesco 95 for the last two tanks (almost empty on filling 50-55l) and get the same mpg as before and this time I didn't reset the ECU so it either learns from the knock sensor or doesn't make a difference.

So in my case spending around 8p/liter more earned me no more mpg and no noticeable performance increase, I will not argue that the Shell and BP petrol is better quality and probably help keep the engine clean internally but think I will stick to the lower price per liter fuel even if it is from Shell or a well know maker rather than the supermarket.

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You don't need to reset the ECU going from high grade to low grade, only the other way round, the cheap stuff would cause damage at high revs in some cars if the ECU didn't restrict the power, once its got the good stuff in you can reset it and restore full power.

If you didn't change your driving style for the new fuel then you would not notice an increase, think about it. The economy is dictated by your right foot. If you still sprayed the same amount in with your right foot then the economy would stay static but the cost would rise by 8p a litre, thats why people claim 'but it didn't make a difference and cost me 8p a litre more! what a con!' lol

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You don't need to reset the ECU going from high grade to low grade, only the other way round, the cheap stuff would cause damage at high revs in some cars if the ECU didn't restrict the power, once its got the good stuff in you can reset it and restore full power.

If you didn't change your driving style for the new fuel then you would not notice an increase, think about it. The economy is dictated by your right foot. If you still sprayed the same amount in with your right foot then the economy would stay static but the cost would rise by 8p a litre, thats why people claim 'but it didn't make a difference and cost me 8p a litre more! what a con!' lol

I would disagree slightly about the economy and driving style, I would presume if you don't maintain the same style ("driving miss daisy in my case") then how can you compare fuel efficiency. If as you put it my right foot goes to a position to give me the speed/acceleration I need then if the octane is higher I should either get to the speed I want with less foot travel or for less time or go faster. If the higher octane fuel burns more efficiently then would the engine not give the same output for less fuel isn't that the whole economy argument "more or the same for less"!

Compare it to a fire, burn wood (low energy efficiency) need more wood to heat the fire, use coal (higher energy efficiency concentrated carbon form) need less volume to produce similar heat outputs.

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Well shit me sideways. Never knew that. Just looked it up in the manual and there is indeed a fuel connector control in the 5, looks to be drivers side footwell on the centre console at that flap in the bottom.

It says this is only the 4afe engine with cat that has it (a yank only engine?) and this is apparently for running American 91 Octane 'Fuelweiser' :laugh2:

Connect it together to run on all american super super low grade, pull the connectors apart for 95 grade or higher.

Of course this is where you say 'but mine was a 3SGE' and then I will be confused haha. Or wonder if this is a prefacelift manual, hmmm :think:

got me a manual lol, the picture shows the glove box on "the wrong side" so im taking that as yank spec

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I would disagree slightly about the economy and driving style, I would presume if you don't maintain the same style ("driving miss daisy in my case") then how can you compare fuel efficiency. If as you put it my right foot goes to a position to give me the speed/acceleration I need then if the octane is higher I should either get to the speed I want with less foot travel or for less time or go faster. If the higher octane fuel burns more efficiently then would the engine not give the same output for less fuel isn't that the whole economy argument "more or the same for less"!

Compare it to a fire, burn wood (low energy efficiency) need more wood to heat the fire, use coal (higher energy efficiency concentrated carbon form) need less volume to produce similar heat outputs.

The throttle pedal controls the flow of fuel. The throttle doesn't discriminate between 95 or 99, it sprays the same amount in regardless, it depends on how much you press the pedal. The idea is you use much less foot travel to accelerate to a given speed the higher the RON and therefore this is spraying much less fuel in and therefore you get better economy as a result.

Driving sedately is the ideal way to notice the difference. Try it out on whatever you have in there at the moment. Find what the absolute minimum amount of gas is that you can give your car to make it accelerate. Then try it again on 99 and you should see it pulling stronger with less.....

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My take on this is, if someone like Joe has the means to actually see the difference, I'll go with that.

I don't get a chance to put V Power in often as possible there isn't one that close. However, we have a Tesco near us so use Momentum 99. (Even cheaper with fuelsave point.)

This last week I had a gas training course to attend just outside of Birmingham, a trip of just over 200 miles from me. The car had no bars left on the gauge so living dangerously. Haha. I put in £40, drove to Birmingham and back then drove to and from work on Friday and Saturday and still have 2 bars left on the gauge.

I'll never get exact MPG results from that, really not scientific enough, but I was chuffed with that.

Higher octane fuel will always be better, whether you can see the results or not. You'll likely notice the difference more when you change your spark plugs.

As someone said, this topic has been done to death but you'll always have your own preference.

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However, we have a Tesco near us so use Momentum 99. (Even cheaper with fuelsave point.)

Thats a very good point not mentioned yet. Promotions.

Tesco do fuelsave and also clubcard points on fuel. Shell do a rewards system and you can get money off or airmiles, and BP does nectarpoints, which you can spend in argos.

Things like that make a difference to the overall economy too. You really need a calculator to work this stuff out as it gets kind of 'moneysavingexpert' the more you look at it lol.

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you have to be careful with shell as i got caught out. if the shell garage isn't run by shell itself and is franchised out, the chances of it being proper Vpower stuff will be slim. I only know this as I was talking to the tanker driver after I filled up with £50 worth of "Vpower" and the driver was in a Tesco 99 wagon. he said the the majority of franchised shell petrol stations he fills up use the Tesco 99 fuel. safe to say i was pissed as i spent £1.30 on so called Vpower when i could have gone less than 1/4 mile up the road and paid £1.23 for 99.

so... when in Inverness.... don't go to shell....

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If that was actually true Trading Standards would go livid. Anyway the tanker driver is talking shit. There is only one main distribution site in Scotland, Grangemouth, and fuel companies use each others tankers especially to outlying areas. Tesco don't make fuel and only buy on the open markets. Their 99 is the minimum spec they they use and basically it is EU imported into SE England Thames storage facilities. They also buy from Shell and BP and in fact some of the 99 sold by TESCO outwith main population areas is really SHELL / BP. What you bought was genuine Shell V-Power sold to Tesco at market rates from Scottish distribution.

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I've been to shell stations and before I've had the chance to hand over my club card the cashier has swiped his/her own! And then gives me a number to phone to get my points added on lol. Thats happened at a few places too. They have the best fuel but tbh I don't trust the franchised ones either

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If that was actually true Trading Standards would go livid. Anyway the tanker driver is talking shit. There is only one main distribution site in Scotland, Grangemouth, and fuel companies use each others tankers especially to outlying areas. Tesco don't make fuel and only buy on the open markets. Their 99 is the minimum spec they they use and basically it is EU imported into SE England Thames storage facilities. They also buy from Shell and BP and in fact some of the 99 sold by TESCO outwith main population areas is really SHELL / BP. What you bought was genuine Shell V-Power sold to Tesco at market rates from Scottish distribution.

so way would there have been a tesco 99 wagon filling the pipes in a shell garage? only going on what the driver said. BUT i know this has been an issue as well on IMOC about shell franchises

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The throttle pedal controls the flow of fuel. The throttle doesn't discriminate between 95 or 99, it sprays the same amount in regardless, it depends on how much you press the pedal. The idea is you use much less foot travel to accelerate to a given speed the higher the RON and therefore this is spraying much less fuel in and therefore you get better economy as a result.

Driving sedately is the ideal way to notice the difference. Try it out on whatever you have in there at the moment. Find what the absolute minimum amount of gas is that you can give your car to make it accelerate. Then try it again on 99 and you should see it pulling stronger with less.....

I think that is what I said if I press the throttle the same with higher octane I should get more speed/acceleration or similarly the same with less pedal travel i.e. less fuel. and as for driving sedately that is how I normally drive.

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