535i fuel consumption

[ngruzevs@optusnet.com.au]

I have a 1989 535i which I have owned for three months, it has done 197000Kms.

After the first three months of city driving the car has averaged 20L/100 (11.75mpg), this figure is not from the OBC. The OBC CONS1 display shows 99.9L/100 :( and the Ave speed indicates 299Km. I don't know what's going on with the OBC.

The range display seems to be more accurate until I get down to 1/4 of a tank, a few times the range has gone from 100K to 40K in a matter of 5min. Then I turn the ignition key off and turn it on, then the range reports over 100K.

Ignoring the OBC issues, what type of fuel consumption should I be getting (City driving)? I'm fairly gentle on the accelerator most times.

[Dave M]

I don't have a 535, but will speculate that you probably aren't far from the norm if its serious stop and go driving. If its mixed city/HW, then you might have an issue. Since your OBC has issues, try taking it out for a calculated run on the HW with a full tank. Stick to the speed limit and fill up when you get back. Do the math to see what your pure HW mileage is like. Other than the mileage, how does it run. Hows the idle? Hows the power throughout the rpm range? Does it 'miss'?

Maintenance questions:

Plug condition?
O2 sensor changed in the last, I dunno, 40-50k?
Vacuum leaks?

As for the gas gauge and OBC range featue, I believe its somewhat common. My gauge dives fast between 2/3 and 1/3, then sits forever.

Someone with a 535 will be along soon. I'm just up early killin time ;)

Dave

[ngruzevs@optusnet.com.au]

Thanks Dave, you raise some good points.

The 535i idles roughly compared to my 2.5 Subaru. I'm not sure if it's normal, I don't have another 535i to compare with.

The last owner took it to a BMW specialist just before I bought the vehicle, the report stated that -

1.The engine mounts were harsh
2.Fuel Injectors were noisy

I'll take the car for a run tomorrow and then do the math :)

[kick7ca]

I have a 1989 535i which I have owned for three months, it has done 197000Kms.

After the first three months of city driving the car has averaged 20L/100 (11.75mpg), this figure is not from the OBC. The OBC CONS1 display shows 99.9L/100 :( and the Ave speed indicates 299Km. I don't know what's going on with the OBC.

The range display seems to be more accurate until I get down to 1/4 of a tank, a few times the range has gone from 100K to 40K in a matter of 5min. Then I turn the ignition key off and turn it on, then the range reports over 100K.

Ignoring the OBC issues, what type of fuel consumption should I be getting (City driving)? I'm fairly gentle on the accelerator most times.

I have a 535im and do 100% city stop and go driving. All maintainence is up to date and I've changed the oxygen sensor. If I try really hard I can manage 16-17 mpg, but my longer historical average is like 12mpg, from stomping the gas too much I guess, and sitting at stop lights.
What I will say is that the OBC may not be that accurate, I still seem to get 2 weeks out of a tank and overall I'd say the car my car is reasonable on gas for the tank that it is.

[Qube]

20L/100 is insane. When I drive "spiritedly" through a full tank (70+L!!) I get about 14L/100. Definitely need to get it checked out.

NB: avg usually is about 12L/100.

[dennyg]

I get about twenty two mpg highway and 15 in city with a heavy foot. I was getting 27 highway but I changed differential to 4.27 from the 3.91.....I like the added power in town but am paying a premium for doing it. Does anyone own a 535 that doesn't idle rough?

[JerseySi]

95% of my driving is in town, stop/start - the other 5% is out of town/at night, where I cna cruise a little more around 50mph..
My average is always between 13 & 14mpg.. It will rise to around 16-17mpg when i'm out of town, but drop once I get back into traffic..
(1988 535i auto for reference)

Your 11.7 mpg sounds a little on the thirsty side, but then I've seen that sort of figure too... try changing fuel brands - I found it helped for me oddly enough!

Hope this helps!

[Steve's5]

Morning,

Like youself we bought a 535I a few months ago.

A recent trip of 1728k's (Mildura to Canberra and return) gave us approx 10.5 L/100km- stuck to 110k speed limit (wife and child on board) The car has done very few K's <28k and ran really well. Hot days aircon most of the time.

Can't give city figures as we don't live in one.

Engine idles well but hunts a little when cold for 15-30 seconds

Very happy with car and look forward to next trip.

[e34m30SF]

One thing you could try is the air filter. I changed that and my hwy mileage went from 16.7 to about 19. Not great, but when my car was built, EPA had it at 15/19, so as long as i'm in between those two, i'm content.

My O2 sensor is the next thing to change.

And I've grown accustomed to a lumpy idle in 535i's. Weren't these engines designed in the early 80s or late 70s, without all of the electronic sensors and stuff?

[Jon K]

Put (6) 42# fuel injectors in place of stock 17# fuel injectors, then we'll talk about fuel consumption.

http://blowneuroz.com/mygallery/E34%20525i%20Turbo%20Exhaust/richbitch.jpg

[Paul in NZ]

i wouldnt describe the idle as rough.the engine speed fluctuates jut a little bit but it is normally hardly noticeable on the tacho.Every now and then it will fluctuate by a hundred revs or so,but the next stop is always fine.A blip of the throttle always seems to settle it back to a 700 or 750 rpm idle.My average is 19.3 mpg slowly climbing bck up from 17 which it was doing with a bad rotor and dizzie cap.My 19.3 is mainly highway but with traffic lights and a steep hill at the end of each day.

[ngruzevs@optusnet.com.au]

I filled up today after filling up full last Wednesday. I had done 180Ks since Wednesday and I put 35 litres into the car today.

The fuel economy works out to be approx 19.5 L/100. Most of the driving was stop start city traffic apart from one freeway run.

I love my 535i, but the fuel consumption is killing me.

Thanks for all your comments, I'll start with the O2 sensor :)

[BigKriss]

I can't get under 12L for highway runs and 16-20L for all city driving is common also. Definitely change the o2 sensor, mine's never been replaced.

[myles]

I get about 14-15l/100km around town in my car and about 9l/100km on the highway. Fully stock setup.

[javoresku]

By Route:
Highway: 12,09 l/100km 987 km and 119 l
City: 15,45 l/100km 2.658 km and 411 l

By Driving style:
moderate: 11,29 l/100km 1.086 km and 123 l
not so moderate: 15,94 l/100km 2.559 km and 408 l
Overall:
14,55 l/100km 3.645 km and 530 l

[The Bigfella]

I just took the M5 to Brisbane to run the new engine in and got back today. When I got to Bris. the engine had 1,100km on it and had used 9.9l /100 - it wasn't driven for economy, as I was constantly varying the speed. Touched 160 once (a friend has a long driveway in sugar cane country on the way up). It got much more flexibility training after its oil and filter change and has done some warp factor work and had a fun time on the Lions Rd. I'm not sure how long the Lions Rd is (maybe 50km?) but it dropped the "fuel remaining" readout by 270km. With 2,200km on it now it has averaged 10.4l/100km

If I recall when we took the 535i up North, it didn't get much better consumption than the M5.

[Derek A.]

M5's tend to get better fuel economy at regular steady highway cruise speeds. Engage the warp drive and the consumption goes way up.

My 535i is about 18mpg city and maybe 21 hwy. But those hwy speeds are usually 80-85 mph.

[e34m30SF]

M5's tend to get better fuel economy at regular steady highway cruise speeds. Engage the warp drive and the consumption goes way up.

My 535i is about 18mpg city and maybe 21 hwy. But those hwy speeds are usually 80-85 mph.

How do you get 18mpg city? new air filter/o2 sensor? over-inflation? Or maybe it's the freaking hills in SF that account for an average 16.7mpg.

[Derek A.]

manual transmissions will generally yield better fuel economy than an automatic.

[BFEINZIMER]

i used to get about 12.9 city, and if i drive like a grandpa like 14

[Qube]

Update:

With EAT Chip, filling premium and leadfootitus, it's:

City: 19 MPG
Mixed (More Highway): 21 MPG

[John B.]

I've had my 5 speed 535i for 4.5 years & have never seen less then 18mpg U.S.
Once on a long highway trip I got 26-27 mpg running at 80-85mph but since I installed the EAT chip I can't get over 24mpg highway.