E39 525i Consumption

You should get more than that.  I'll check the figures later at home.

My E39 would have got mid thirties on that journey.  Although I did once have the misfortune to put Asda supermarket fuel in the E39 once prior to doing a Motorway journey (200 miles) and I only got low thirties.

Was it decent fuel?  How mechanically 'fit' is the engine?  How fresh is the oil, how clean are the filters?  Does it do motorway mileage much?

Although once you start going much over about 72mph I have found that the consumption got a bit thirstier.

Tyre pressures? 

You didn't have a roof rack or a dead body in the boot per chance?

Killian

Are your figures based on the OBC or brimming?

I'm finding that while overall consumption with this ('00) 523i is on a par with the last one, its showing 34.8 on the OBC for the last 10k miles or so but probably just a little over 33 on brimming calculations - similar to the '97.

However, with sustained motorway work, similar to what you have described, I'm probably getting around 31.  This figure is probably a little worse than the old one - with that one it didn't seen to make a huge difference how its was driven.

There are 2 things that I reckon might contribute to the conclusions of that comparison.  Firstly, the '00 has dual vanos whereas the '97 had single.  The extra vanos is on the intake side so it makes some sense that facilitating it breathing easier on the intake side would cause it to use a little more fuel.

The second may be just coincidental but the other variables such as driving speed and style has been fairly constant.  I reset the obc around 10k miles ago following a service in November.  For the first 4k miles following it averaged 34.4.  I changed the wheels/tyres from 235/45/17 to 225/55/16 then and since the consumption has improved to 34.8 (in a little over 6k miles).  It might not appear a significant difference overall but on a fairly large sample of miles pre-change then the improvement post change has to be probably better than an extra 1mpg over the later miles.  I'd expect a difference with a smaller, higher profile and narrower wheel/tyre combo as the extra contact patch of the larger one means extra rolling resistance.

I'd expect the auto box on your car to cost about 2-3mpg over a manual.  Take that from the brimming mpg I see on motorway run's it gives you a figure of around 28 - then the gap to your figure is only around 1-2mpg.  While it might be slightly higher than it ought to be, a difference like that doesn't suggest anything major amiss.

What oil was used at the last change (viscosity)?

Edited by Dergside

First, DON'T use the cruise if you want to save petrol.
Second, the Autobox is taking 5mpg form my experience.

I changed air filter, spark plugs etc on my 528i and that improved mpg a little. But never did a proper service to this one anyway.

I sold the 528i to a friend letting him know that there was a "honking" sound from the split engine breather.
Bought the part but could never be bothered to remove the plenum to fit it. Friend too the time to fit it and reported better mpg!
so check all your vaccum hoses etc. I once took the plastic cover off above the injectors and a few of the thin pipes where just a guey mess.

Interesting..
I get roughly 26-28 mpg out of my T5 (2.3 turbo) when driving sensibly to try and squeeze the fuel out a bit - which involves keeping the spinny thing from spinning and no sudden downward movements of my right foot

As an afterthought, I usually use cruise control on motorway journeys - especially when there are 50mph speed scameras...


Edited by Rhys

Andrew Rolland wrote: Try getting your autobox serviced, that could ease up consumption.

???? what do you want to "service"? and oil chance is all you can do. and according to BMW you shouldn't even do this.

Had the oil changed in my 530i and it made bugger all difference in fuel consumption.

As the car had been lying up for about two years before I got it, all fluids were renewe. I'd have to check but I've now got one of those feelings that the g/b & diff oils weren't BMW spec.

kbannon wrote: Really? I thought cruise would have been fine.I'll know next time.

I don't have a 528i but I do have a 728i - 2001 with the double vanos. I don't believe the tale about the cruise not saving fuel. Unlkess its on a diesel car which I am told is is different. If you drive as smooth as you can without the cruise, you will be hard pushed to match the economy obtained by cruise. I drove back from East Germany recently on cruise whenever possible with a full boot and two passengers at around 80 mph and returned 34.5 mpg.
On the way out, driving the same route with the same load, though not as quickly (around 65 to 75) without cruise, I averaged 28.5. My car has done well over 130K miles and performs faultlessly, apart from a propensity to break front springs (4 Chinese? ones to date in 2 years)

Living at the top of a hill,(300 metres) its all uphill on the way home, but the car still does all round about 22 urban, 28 out of town, and 26.5 overall. I would expect the 5 series to do a bit more as it weighs less.
All figures are from the OBC.

I swear by the cruise to such an extent that I had one retrofitted to my 1988 635csi. This usually does about 32 to 33 on a run using cruise - again, according to the OBC.

Typo is reason for edit

Edited by Howard

My E39 530i would get 35mpg at 70mph on the cruise control and about 32 at 80 mph.

I also don't have a problem with cruise control from an economy perspective.

Have you had your fault codes read recently?

Economy figures for you.

525i Auto urban 19.6mpg extra urban 36.2mpg Combined 27.4mpg