Got an e39 525i SE auto and the obc says I'm getting about 16-17mpg around town (car idles about 700-800rpm steadily and my own calculations mirror the obc reading). BMW reckon I should be getting about 25mpg. Basically, zero load, careful driving but the economy doesn't improve. The car was serviced by BMW 2k miles ago for what it's worth. What I haven't done is to take it for a motorway run.
I've read posts here and there and I gather that I should be looking at about 20mpg, if not a tad better, and wondered if the mpg I'm getting is normal/acceptable or whether there may be an issue somewhere.
Any advice is appreciated. Thx.
S.
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The BMW quoted figures for the E39 525i Auto are 19.6 mpg for urban running, 35.8 mpg for extra urban and 27.4 mpg for combined running.
From your thread, it sounds that most of your driving is under urban conditions, which is not always a good thing, if you don`t give it an occasional "Italian Tune" up. !!!!
As your OBC, (which on average read 4 to 5% optimistically) is reading only 16 to 17 mpg, perhaps the engine would also benefit from a fuel injection/system cleaner such as Millers Injection Plus, which is simply added to your fuel tank before filling up, and could make a drastic improvement. !!!!
www.millersoils.co.uk
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From what you say, 19 mpg seems about right. When you can, have the tyre pressure checked and ensure the air filter is clean. Italian tune up and additives will also help improve it.
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Thx guys, will put some Redex in the tank (assume Redex is good enough, yes?). As for "Italian Tune-Up", umm...I best search the forums and see what that means :)
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msm - As you seem to spend a fair proportion of your motoring in urban areas, "The Italian Tune Up" merely involves taking your car out onto a decent stretch of road occasionally, (after adding your Redex/Millers injector cleaner), and taking it up to near max revs in every gear, which will hopefully blast out any carbon build up in the injectors.!!!!!
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Thanks for that info Dude. I'll do that tomorrow. Out of interest, can a slightly blackened air filter affect fuel economy? Thx.
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slightly blackened air filter affect fuel economy? Thx.
Probably
What do you mean by town driving? if you are crawling into the centre of a big town every day then 16-17 mpg is about right.
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I agree that 17 mpg is not far out for town driving. The biggest need for fuel is when accelerating a car and there will be a lot of this in urban stop-start traffic. Also, the 5-Series is a heavy car, so there's a lot to accelerate.
The cold weather that we have at the moment will also have an impact on fuel consumption because the engine will be taking longer to get up to its most economical temperature.
On top of that, the transmission lock-up doesn't come into play at urban speeds. This device is a real fuel saver, so much so that the E39 auto is more economical than the manual on the open road.
I'm not a fan of additives as they can do more harm than good. An occasional open road blast will help keep the engine valve areas clean but I'm not even sure that this will have any efect on fuel consumption.
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Dizzy - would you care to quantify your statement please, as I am considering using Millers diesel Power Plus in my 320d, which not only contains a combustion improver but also cetane incorporating a lubricity additive to protect fuel pumps from low sulphur fuel.????
\"I\'m not a fan of additives as they can do more harm than good.\"
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Dude,
I would never say that *all* additives do harm but it's such a minefield that I personally prefer to stay away from them.
Looking at Redex for a start: This was very popular about 50 years ago when engine design and build was a world apart from today. I was using it for most of the 1960s as an 'upper cylinder lubricant'. The marketters must have known that the engines of the day let so much oil past the pistons that there was no need for a UCL, however I was too green to realise this.
I cannot recall any improvement in the way my engine ran with Redex in the fuel and I noticed no difference when I stopped using it, other than having a bit more money in my pocket. Now Redex seems to be the 'in thing' for cleaning injectors and what-have-you. I doubt its abilities to work wonders on modern engines any more than it did on older ones. 'Cure-all' or 'snake-oil'? I don't know, but my money stays in my pocket.
Millers is a name I respect but I would still be wary of adding anything to the fuel that it wasn't designed for. Sulphur was a very important lubricity constituent of fuel for many years but its place has now been taken by other chemicals. These may or may not work as well as sulphur (certainly there were problems in the very early days) but I would have thought that the fuel chemists have now got it all sorted. I prefer to play safe rather than change the delicately-balanced cocktail of chemicals in fuel by dosing it with something that it wasn't designed for.
That's not a very objective answer to your question, Dude, because there isn't one. However, my Rover 75 has almost the same engine as your 320d and I will obviously not be using fuel additives. It will be interesting to see how many extra multiples of 100,000 miles you get from your engine compared to mine!
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Dizzy,
Very interesting remarks. I read them after dropping some Redex into the tank and whilst I don't really think additives do much myself, I thought I'd give it a try with a small bottle.
I've replaced the air filter and spoke with my local BMW garage. I told them I'd be driving locally and the techie said I should be looking at about 25mpg. First, I think that may be a tad optimistic and the second thought was maybe he's trying to lure me into the workshop ;)
I know town economy figures will always vary between people but what with me driving like Miss Daisy and getting 17mpg makes me think twice. Perhaps all is in order and my figures are faultless. In anycase, I think I'll learn a few things from here anyway.
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I use Valvolene fuel system cleaner. Worked wonders on a 2001 model year 530d SE. I have also had good experience with Red Line injector cleaner.
Auto more economical than manual? can this be true, surely transmission losses are still higher? I'm not knocking, just interested.
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Ben
"Worked wonders on a 2001 model year 530d SE."
Could you please enlarge on the wonders worked on your 530d, whether it was increased mpg and by how much, increase in performance or both - and also what mileage had your engine covered before you started using the valvoline.?????
Referring back to Dizzy`s last posting, I agree with him wholeheartedly on Redex upper cylinder lubricant, which is an absolute waste of money, but am not fully convinced with his argument and stance against Millers Diesel Pwer Plus.!!!!
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Dude,
I haven't really taken a stance against Millers DPP. I said "Millers is a name I respect ... but I am wary of adding anything that the fuel wasn't designed for" (or words to that effect).
I'm sure that using Millers, or any other fuel additive, poses far less risk than adding anything to engine or transmission oils but it is my personal preference to avoid all aftermarket additives.
I spent my working life in the area of diesel engine design and can recall only one additive being recommended by our firm. That was an anti-waxing fuel additive for engines operated in very cold climates, to reduce filter plugging.
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I've just stumbled across an article in the Jan.1998 issue of an American magazine that I used to take called Automotive Engineering.
The article reports the testing of fuel additives claimed to clean engine fuel systems and states that several of the additives were found to significantly *increase* the deposits in intake ports and on valve stems and heads, i.e. do more harm than good. Unfortunately the article doesn't reveal brand names.
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Digital read out on dash read 60k when my dad bought the car, its a spetember 2000 with the 193bhp engine. I think it had been sitting around for ages, had an auction tag on the keys dated a few months prior to the day we purchased it. Bought from BMW finance sale at blackbushe. Didnt drive all that well, hesitation at just over 2k rpm etc, little power, felt rough. Drove it like that for a few hundred miles. Put a bottle of the valvolene stuff in the tank when i filled up and things began to improve. Engine noticeably running better. I wondered how much of this was due to the cetane enhancer in the additive, but it continues to run well with no additive. Run on texaco or shell fuel. If your cars not filled with junk it wont make much difference, but if you have a suspicion it is, and it isnt running well, give it a go i say, it only a few quid. Much cheaper than a diagnostic check up at a dealer.
MPG deffinately increased- got less than 40mpg driving the thing home from auction gently on m25. On a recent trip to the auction in morning traffic it managed an indicated 48.7mpg for the journey. I would stick my neck on the line and say that the additive DID have a positive effect on fuel consumption. Note i did remember to compare economy and running of the car on the new tank of fuel after the one including the additive, with the original few tanks, so as not to confuse the effect of the additives cleaning properties with its cetane enhancing properties. Sorry i dont remember exact figures only memory of improvement around 5mpg. Hard to say how much car would of improved from normal use without additive as it had been sitting, but did drive for a few hundred miles prior to additive with no change.
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Auto more economical than manual? can this be true, surely transmission losses are still higher? I'm not knocking, just interested. >>
Perfectly true, Ben. Steady state motoring with lock-up engaged produces better mpg figures than the equivalent manual car.
The lock-up does what it says; it locks up the torque converter so there's no slippage between engine and wheels. Because the auto has higher overall gearing anyway, mpg improves.
This definitely applies to the 525iSE and I wouldn't be surprised if it also applies to the 530dSE. However, as you probably know, the 530d is generally much heavier on fuel in auto form so I expect the manual still has the edge in overall fuel consumption.
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Steady state motoring with lock-up engaged produces better mpg figures than the equivalent manual car. >>
Just thought I'd clarify what I meant by 'steady state'. I didn't mean constant speed, I meant avoiding repeated bouts of acceleration that are hard enough to make the lock-up disengage.
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Cant you get a gas analyser stuck on the exhaust at a tuning place to see if the thing is running rich and take it from there?
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The car was mot'd before I bought it and it passed without problem. I know they do an emissions test and wondering if that'd show something if the car was running too rich.
S.
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