Guys/Gals,
I have a 1988 528e and it runs perfectly(seems so from the drivers seat). Over the last few months the gas mileage has dropped from about 25-28mpg to around 17! Does anyone have any ideas what this could be ? Or combination of things?

Thank you!

o2 sensor?

change in type of gas offered in your area? winter blends are known for giving lower economy, but usually not that great.

Might want to put this into the e28 subforum.

yeah my mpg on my e34 always says between 18-21. i use to drive 5 miles freeway to work. now i go 2 miles on the streets but milage is at like 15-17 is that normal or 02 sensor could do that? i had trouble passing smog so i think its the 02.

stop and go traffic uses more fuel. does it not?

Driving around Boston I see 20-21mpg, 26-27 on highway at 70+. Stop and go driving takes a toll, if you aren't moving yet the engine is running the mpg is decreasing.