mileage

[Edirtyy808]

im getting only 12.7 avg mpg on my 1990 325is. why is that?

[ak-]

Because you need a tune up

[jlevie]

Smoke test the engine, fix any leaks and adjust the valves. If they are 10 years old replace the ignition wires and distributor and install a fresh set of NGK ZGR5A plugs. The O2 sensor has a service life of 100k. If that applies replace the sensor. Check rail fuel pressure and verify that the engine is running at normal temperature (80C) and check the ECT sensor for correct operation.