: fuel economy 535i

12-17-2008, 01:09 AM
My pet 535i which I purchased from a little old lDY SEPT 2007 has now done 146k and is giving 19.5l per100k.

Has rough idle and hunts a little other than that smooth but I feel that I should attempt to get better mpg. Have not checked anythng eg. sparkplugs, whqtever.

Any chronic issues?


david, brisbane.

bimmer dot info
12-17-2008, 06:40 AM
19.5l per 100k is about 12.3 mpg.
It is on the bad side. I'd go ahead and check the ignition system, fuel filter, and replace the o2 sensor if it is old. Might be worth checking the compression and making sure the exhaust is not clogged up.
All that said.. I would not expect you to ever see more than 19 mpg in the city with this car.

12-19-2008, 10:25 AM
Rough idle could be caused by vacuum leaks, or as you mentioned, spark plugs. Little old ladies never change the air filter, either.

12-27-2008, 12:44 AM
Thank you both for your advice.

Did a little ore detective work. Have done some 80 to 100k drives in the last few days goiung to various family Christmas events and the beach. speed limit is 100k or 110k. At both speeds the dashboard (vacumn gauge I think) sowed 10 to 12 l per 100k. When I throttle back on the highway the gauge drops down below, well below 10, say 4 or so. When i pull up at the lights the gauge godes of the dial to beyond 30 l per 100, and does the hunting surging.

Without ignoring suggestions made to date (hey i'm at the beach and I can't do everything) does my vacumn gauge info give you any thoughts.

Re comments re 19mpg. happy with that. The car does about 10,000k per year so I don't need some petrol miser.

By the away has anybody open one of these up. The maximum speed limit is 110K on only two roads in the whole stae so at that speed the engine is just getting a nice rasp in its note. Its so good to ride in on the highway.

Regards and merry christmas


12-27-2008, 01:05 AM
I'm getting a little higher than 19mpg....I think I'm around 22-24 with my 535i. I also have some kind of problem and I think once I fix said problem my car will possibly have better mileage yet.

In regards to your speed question, the car can cruise at higher speeds comfortably. Sometimes it just begs to be driven fast. I can neither confirm nor deny driving my 535i for 300ish km at 150-180kph. Like most German cars, it's quite comfortable at higher speeds. I bought mine for that reason...I put on quite a few km's on my car and a lot of it is highway driving. :)