I get horrible gas milage (excessive fuel consumption)

[TheMuffinMaster]

Hi everyone
I have bought and e36 318i with the m40b18 engine about half a year ago i was getting poor gas milage from the begining but now it started really to bother me i get 5 km per 1 liter which is 20 liters for 100 kilometers which is 11 mpg
Is this sopposed to be this way? Because i dont think so
I drive preaty slow of course i sometimes slide a corner or floor it in first gear but still it is just stupid high fuel consumption
Please advice me what can it come from and what can i do with is

[JDStrickland]

M40? are you sure? You should have the M42 for the OBD I motor. You have a Euro. spec car, so you might have a different engine than we have in the states for this car.

I would start with a compression test.

[TheMuffinMaster]

Will do thanks

[Nate94]

Also try a new O2 sensor, and clean your MAF sensor in the intact tract, that helped me immensely.


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[clintsusa]

Do I need to replace all O2 sensors? I have a 1994 e36

[MIKYZZ4]

(1994-2018)=24yrs, a lot of periodic,preventive maintenance should have been performed in that amount of time .
So yes, I would replace pre-cat & post cat sensors.
Sparkplugs if over 5yo or 30~50k miles dependent on condition after inspection.

I suspect intake leaks as the primary cause of your terrible fuel mileage,
so I would inspect all rubber intake boots and associated hoses for cracks.
Another way to locate hard to find leaks is a smoke test.

[marvinstockman]

Check for dragging brakes, by driving around for 15 to 20 minutes. Stop car, check all wheels to see if one is much hotter than the others. Note, fronts will normally be hotter than the backs.

To check highway mpg, fill car, then drive for 15 minutes on highway, stop at a gas station, and fill again. Do the math: miles driven/gallons used.

Check for clogged exhaust/cat converter.

[Eric93se]

You only have to replace the pre-cat sensors.