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)?

UweM3 wrote: 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.

Getting you autobox serviced means getting your oil changed and filter changed.

Ignore BMWs advice on its sealed for life policy.

After my E60s autobox was serviced I noticed a slight improvement in consumption.

I would agree with Howard.

My E39 got the best economy, 39.6 mpg with the cruise set at 72mph from Glasgow Airport to Perth.  Dropping to 50mph on the cruise when speed limits dictated thru Glasgow city centre M8.

My E60 returned it's best ever mpg of 36.6 with the cruise set at 60mph from Inverness to Perth.  I might have got more once but I didn't take a picture of it to remind me (yeah I know I'm sad)

I would have never got either if I had used my right foot, IMO.

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?

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

It is indeed noticeable once you start going over 70mph figures start to head south, wind resistance etc all gets worse the faster you go.

Can you try the same journey at 70mph K and see how you get on?

Still wouldn't think that you would get as low as 26 ish at 80mph even in an auto.

Sorry, I haven't found the figures for you yet.

Economy figures for you.

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

I was having another think about this.

You know the fuel in America has a lower octane rating that we have here or something similar, as they always mention that power is less on cars when run on limpwristed American fuel.

As yours is a Japanese import is it designed to run on a different grade of fuel? 

If you are using ordinary 95 octane unleaded might you get lower mpg if the engine was meant to be running on higher octane stuff and the engine can't adjust itself for a reason unknown to me and gives you lower mpg?

31mpg would be o.k. at that speed.

Nowt wrong with it.

Killian,

next time, rather than relying on the OBC to tell you your mpg. Work it out the old fasioned way first

Ever heard the saying:

To err is human but to completely f**k something up requires a computer.

Peter Fenwick wrote: Killian, next time, rather than relying on the OBC to tell you your mpg. Work it out the old fasioned way first Ever heard the saying: To err is human but to completely f**k something up requires a computer.

Lol!

Peter Fenwick wrote: To err is human but to completely f**k something up requires a computer.

Nah, a person will do just as good a job as a computer to f**k something up.  You obviously haven't worked with some of my colleagues!

My OBC says I average 34.8 with the 2.8.

The best I've ever obtained was 39.2 on a run to essex.

Nigel wrote: My OBC says I average 34.8 with the 2.8. The best I've ever obtained was 39.2 on a run to essex.

That's very good Nigel.  My E39 with the 2.5 (auto) would only average somewhere between 29 and 31 from memory with 39.something recorded on a run (using VPower) from Glasgow Airport to Perth. 

Peter Fenwick wrote: That's because Nigel is an old man and drives everywhere at 35 mph

Ah, thanks for clearing that one up Peter.

It's more likely that I'm almost always on the "extra urban" side of things.

I rarely use it around town, my wife and daughter both have the smart for two city cars now, the wifes being the soft top, and they are so much fun to drive around town I usually nick one of those.