E39 530d fuel economy

[[TW]Fox]

Hi guys,

I can't help thinking that the fuel economy our 530d returns lately is really rather crap.

I just drove it 150 miles from Devon to Hampshire and returned 37.1mpg. For context, the same trip driven in the same way in my 530i yields about 32mpg. My parents drove up an hour in front of me in 3.0 Z4 and got... 35mpg.

Clearly this isn't right - it barely ever gets above 40mpg even on long motorway journeys. It always used to be far more economical.

What could be causing this? Car is a 2002 530d with 69k on the clock. I dont know if its just me but it also sounds a bit more diesely and clattery than it used to, and there is noticeable cabin vibration at idle.

Any ideas?

[gizlaroc]

Could be anything, fuel sensor, temp sensors, splits in the intake pipes etc. etc.

Most things would be very cheap to replace.


I think 37 from an E39 is good, I take it that it's a manual??

[[TW]Fox]

Yes, its a manual. I think its very poor - this is not city driving we are talking about.

On a pure Motorway run it wont even crack 45mpg and this is only at less than 80mph, speeds which will see my 530i return 37-38mpg.

I never remember it being this inefficient before, there has definately been some sort of degredation.

[clonmult]

37+ mpg still isn't bad for a car of such size though. Would a 525d be any better?

I'm thinking ahead and considering an E39 in some diesel form, either 525 or 530 as the next car. Although a 523 or 525 petrol is equally tempting.

[timwatsham]

I had a 530d for 18 months and averaged 42.1 over 44k between 114k and 158k. It had been remapped but I did a lot of motorway distance. Last few tanks were around 44.5mpg when doing 70ish on cruise control.

Great car.

[ChrisKKKTurbo]

timwatsham said:

I had a 530d for 18 months and averaged 42.1 over 44k between 114k and 158k. It had been remapped but I did a lot of motorway distance. Last few tanks were around 44.5mpg when doing 70ish on cruise control.

Great car.

ditto with 188K miles

[[TW]Fox]

clonmult said:

37+ mpg still isn't bad for a car of such size though.

It's a diesel - my petrol 530i can crack 37mpg which IS impressive, for a 530d its dissapointing which leads me to think there is something wrong with it.

[clonmult]

[TW]Fox said:

clonmult said:

37+ mpg still isn't bad for a car of such size though.

It's a diesel - my petrol 530i can crack 37mpg which IS impressive, for a 530d its dissapointing which leads me to think there is something wrong with it.

If a petrol 530 can get 37mpg, then it is pretty poor for the diesel. Gives me food for thought on the next car. Definitely a 5 series, 523 or up ...

[Neil.D]

Do you keep on top of the tyre pressures?

[darren no 7]

mine was remaped and used to get 45 to 50mpg on a run

[gizlaroc]

Have you had someone scan it???

Will probably tell you straight away what it is.

[[TW]Fox]

Neil.D said:

Do you keep on top of the tyre pressures?

Yup - absolutely spot on.