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Discussion Starter · #1 ·
I would like to check with other 525i owners on their fuel consumption please.
Mine seems quite high to me at 17litres per 100klms - 16.6 miles per gallon if I've done the conversion correctly.

Admittedly they've all been mostly short trips so far.
Still seems very high though compared to previous vehicles driven under the same conditions. Mostly they have ranged from Supercharged 1.8litres to 3litre V6 and they mostly averaged around 10 to 13litres/100klms.

The 525i is very smooth and has good pull when required, so I don't think its in limp mode or anything like that.
I do notice than the economy meter under normal driving hovers around the 5l/100k up to about 20l/100k but as soon as I stop for lights or traffic, the needle swoops up the far end and disappears out of the meter well over 30l/100k.

Could this be an indication of a problem, or is it normal just because of the high vacuum?
 

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Discussion Starter · #3 ·
You got a Pre cat lambda sensor on yours? number 20 http://www.realoem.com/bmw/showparts.do?model=HJ62&mospid=47393&btnr=18_0172&hg=18&fg=10

If yes and it's the original item then I'd be looking at replacing it, it will have lost efficiency by now.
Hi Ronnie.

Thanks for such a quick response.
Yes - I do see a pre-cat sensor there, but my exhaust system also looks slightly different to the one shown.
I have the two pipes from the manifold running back to a zig-zag section as shown, except that my zig-zag or "S-bend" looks like it remains as two seperate pipes inside a common cover.
After this where the two pipes come out now over in the middle of the car, there is a section where they are joined by a small crossover and thats where the Lambda sensor is.

But then my two pipes continue seperately and have their own Cat each - not like the big combined unit shown on the parts picture you linked to.

Then the two pipes go into a combined muffler just in front of the rear axle, but its not as big or offset as the large unit shown in the RealOEM rear exhaust section. The exhaust still come out as two pipes and carry over to the large twin pipe muffler at the rear.

Its definetly not aftermarket - its all BMW factory stuff with BMW stampings.
I wonder if it been lifted from a M5 or something because one thing it has got is a very nice low throaty sound at idle and when accelerating. Its one of the nicest things about the car.

Also though - if the Lambda sensor was worn out or out of spec, wouldn't I get a service message on the dashboard?

best regards,
 

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Discussion Starter · #5 ·
You will only get a fault code if the heater side OR the sensor actually fails internally, not if it loses efficiency. :thumbsup
Okay - thanks Ronnie.
Any hints as to where to pick up a cheap one rather than the dealer?
I'm in Sydney - Australia which doesn't help, but perhaps you have a good international supplier you could recommend?
 

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Just a quick mention, i get 32 mpg on a constant 70mph basis on the motorway... and around 25-26mpg around my town... Thats what you should be getting with yours there or there abouts... floor it though and she drinks it...

Obviously, i don't know anything about the dealers in sydney.

But i have found a few links

http://www.bemw.com.au/index.htm

http://www.bromspecbmw.com/

http://www.sydneyprestige.com.au/

Maybe ronnie has heard of a specificially recommended indy in sydney, and i believe one of the moderators is from australia... so hopefully we can point you in the right direction..:thumbsup
 

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Discussion Starter · #7 ·
Thats great Mighty and Ronnie - I appreciate the assist.
I'll try replacing that Lambda sensor first and look for improvements.
I would expect around 24 - 27mpg for the driving I do, and around 33 - 35mpg on the freeway should be within reach.
But my 17mpg is just a bit too low.
Thanks for the links. I know Bromspec and the original owner was a clever guy. But last I heard it had become a bit expensive. I'll troll the other links and some overseas suppliers.

Thanks again and best regards,
 
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