My 1992 525i (auto trans) wagon is getting 9-10 mpg in the city, but when I drive on the highway the computer and the vacume mpg gage on the instrument cluster says I get 20-23 mpg.

What mpg can I expect?

Any ideas if this signals a vacume leak? ... Or needs a tune up?

I did a STOMP test and no codes came up.

There are 160,000 on the car and I don't have any service history. Thanks fro your feedback. I'm new to the BMW world.

I have owned this car for 3 month now and I am much more familiar with it's mechanical condition. First of all, I cleaned the Transmission Gear Selector Switch and it really improved the gas mileage.; and all my LCD pixels are now working. Secondly, I serviced the transmisison and found that there was too much fluid in the tranny. This too affected the gas mileage on the highway.

My average gas mileage is now 14 city and 24 highway, which isn't that bad. However, I still think the city mileage ought to be better. Moreover, when I am in heavy city traffic, my city MPG can be as low as 10-12 MPG. I'm wondering if this could be due to a bad fuel injector leaking fuel? Any thoughts on that?

Any dealership will be able to do an injector test for you.


Pull your plugs, take a pic, lets see what they look like...
Could probably use a new ignition, plugs, wires, cap, run some injector cleaner if they are fine and not leaking, should help out a little

Prior writing my post, I used fuel injector cleaner and all my plugs appear to be burning clean. I also disconnected all my sender leads (MAF, TPS) and checked for vacume leaks. The only thing I can say is that at idle I can smell unburnt fuel.... as is an overly rich mixture.

With regards to doing a fuel injector test, can this be done with one of those testers that plugs in to the 20-pin Diagnostic Head?

Any other ideas would be appreciated.