In my quest to take the Insignia's average fuel economy past 70mpg I tried a tankful of BP Ultimate diesel. I'm somewhat surprised to report that the economy (on the same roads, same conditions, and same speed) has dropped from 69 to 45(!).
Now, I don't entirely trust the garage that I bought the fuel from - being a BP franchise but with a very strange trading name - but clearly they've screwed up their formulation somewhere.
Shirty email sent to BP asking for the price difference between this and their bog standard fuel to be refunded.
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When I first got a diesel (Mondeo in 2003) I found premium diesel got me a tiny bit more MPG but not worth the extra. And it did run smoother.
My current, more powerful, diesel is a VW 170PS engined car... and it can easily do a lot more MPG than the Mondeo. Trouble is every now and then I'll accelerate harder than you need to and MPG drops a bit :-) But why else have the 170PS instead of the 140PS engine??? :-)
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69 mpg to 45 mpg seems incredible, something is wrong and I wouldn't have thought all that gap is down to the fuel spec. I had a Focus Econetic that ran noticeably better on Ultimate but my current Santa Fe runs no better or worse on Shell, BP or Tesco with a splash of Millers Diesel Power thrown in if I remember.
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I don't recall ever getting significantly better economy from ultimate/V-Power diesel, I definitely DID get better MPG from Shell/BP standard diesel than from whatever Morrisons dispense with the Tesco/Sainsburys stuff somewhere in between - all subjective of course. What I would say is that my cars appeared smoother on the premium stuff, but not worth the additional cost.
Down under I run my petrol car entirely on Shell V-Power, must admit that the one time I used BP Ultimate (petrol) it gave even better economy (50+mpg), however I get 3p/l off the Shell V-Power via supermarket offers and that means I'm paying less than 90p/l for 98RON V-Power right now ;-)
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Normally I'd blame myself and environmental factors too, but this is literally the same journey of about 90 miles, in the same conditions, at 76mph on cruise with the AC on and calm winds.
I ran the tank down to about 2 litres capacity so the fuel is nearly entirely BP Ultimate. New car so unlikely to have sucked crud from the bottom of the tank. DPF regen happened last week so it's not that.
Do modern diesels still have a fuel filter? Might have a look for water later today.
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I'd blame the car. Has the egr gummed up yet? the egr cooler split yet? almost certainly the turbo intercooler hose is about to go.
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Over the years I have found that the quality of diesel can vary dramatically, some causing noise and smoke, some smooth and quiet. Possibly a duff batch, missed additive package, less than honest retailer, who knows. I would run a couple of tanks of fuel from different suppliers through the car before getting too wound up.
Last edited by: Old Navy on Tue 9 Jul 13 at 08:35
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Has the consumption returned to "normal" on refilling with the standard brew?
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>> Has the consumption returned to "normal" on refilling with the standard brew?
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Don't know yet, I'm only half-way through the tank. It normally does nearly a 1000 miles to a tank, but I reckon I'm only going to get about 650 out of this.
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>> I'd blame the car. Has the egr gummed up yet? the egr cooler split yet?
>> almost certainly the turbo intercooler hose is about to go.
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I'm going to make a fortune when I invent a device that lets you slap someone in the face over the internet. ;-)
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If the fuel consumption has increased dramatically, I'd guess contamination. Batch bought in from the red diesel alchemists? Petrol in the mix? Have a sample taken after you've drained off your fuel tank ASAP. Or flat tyres:)
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I'm now going to stick to Shell Nitro diesel. There has been a marked improvement in fuel consumption in my CR-V by just over 5mpg.
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Hmm. I did suggest to BP that they dip the the tanks at this particular station, so we'll see. Just had a read of the manual and the car will warn of water in the fuel.
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If I were you I would put a double dose of Millers diesel additive in the tank pronto.
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Would current high temperature be a factor?
Come to think of it does high OAT affect your Airbus much?
Back in seventies Brittannia were usinf 737 200ADV's, in a pretty marginal operation, flying to Med off the then 5400 foot runway at Leeds. IIRC OAT over 20 and a tech stop for fuel was needed, usually at Luton.
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Ambient temperature has not affected the running of any diesel I have owned to the extent of FFs problem. The average driver would probably not notice any temperature effect. Us OCD diesel users however...........:-)
Last edited by: Old Navy on Tue 9 Jul 13 at 09:39
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Our Honda Idtec seems very sensitive to fuel. I haven't yet tried the expensive Total stuff but I can't help thinking that some suppliers are on the make by leaving out additives and such-like.
How can you tell when the DPF regenerates? Honda says you might notice a bit of white smoke but in 8,000 varied kilometres I haven't yet.
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Did 385 miles yesterday in temperatures ranging from 20C early in the day to 29C later. Fuel consumption marginally better than usual for that particular journey at 48mpg. Normally get around 46mpg. Morrisons standard diesel. May just have been traffic conditions of course. Fairly light yesterday.
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Yep, aero engine performance reduces as outside air temperature increases. It's limited by fan speeds and EGTs, so warmer (ie less dense) air means the engine needs to run faster / hotter to deliver the same performance.
It's not a huge issue 99% of the time (in fact, we fool the engine into thinking it's warmer outside than it actually is on most takeoffs*) but when you're at maximum weight in a hot, high, airfield it certainly has an impact.
* en.wikipedia.org/wiki/Flex_temp
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Are you relying on the cars fuel computer, or have you done it the accurate way with a calculator?
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>> Are you relying on the cars fuel computer, or have you done it the accurate
>> way with a calculator?
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The car's fuel computer, but on the last tank it was accurate to within 5%.
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I've used V-Power diesel for a few tanks in the 320d. Absolutely no perceptible difference to performance, engine characteristics, or fuel economy / tank range. A complete waste of money, IMHO.
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So, have done 1500 miles over the last few days.
Tank emptied and refilled with Tesco Value Diesel. The BP Ultimate fuel delivered, eventually, 53.2mpg from a tankful.
The Tesco diesel, on the other hand, returned 76.1. Your mileage may vary. BP never replied to my email so sent another to Trading Standards suggesting they dip the tanks at this particular garage.
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>> So, have done 1500 miles over the last few days.
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>> Tank emptied and refilled with Tesco Value Diesel. The BP Ultimate fuel delivered, eventually, 53.2mpg
>> from a tankful.
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>> The Tesco diesel, on the other hand, returned 76.1. Your mileage may vary.
Very strange. Assuming someone didn't nick a few gallons from your tank it's difficult to imagine what could have caused that, especially with a diesel.
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Friend of mine recently picked up a batch of really really rubbish BP diesel in a garage in Newmarket. Performance and Economy fell off a cliff.
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Since succumbing to a diesel engine I have been trying a range of fuels after a chance refill at one particular supermarket group station showed a marked reduction in fuel consumption.
I've discovered it seems to be a lottery.
Today, for the first time, I tried Avia 'Plus' diesel from an ordinary filling station. It's 10c a litre dearer than the supermarkets but instantly the indicated fuel consumption dropped significantly and the car 'feels' much smoother.
If a 7.5 per cent price premium equals a 10 per cent improvement in consumption and the car feels better then I guess I'm on the right side. But should all these variations exist?
The old Prelude did 34-35mpg week in, week out, year in, year out no matter what 95 or 98 unleaded went into it, and always ran (runs) like a sewing machine.
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Never tried it. After reading this, don't think I'll bother. Thanks!
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BP Ultimate is rubbish - rtj70
