While the problem has been present for years, I am recently reminded after driving a 96 855 t5 instead of my 96 854 t5. The borrowed car consistently showed about 10% better fuel economy than my ride. This is magnified in strangeness as my car has the IPD chip and exhaust and the 855 had is stock. On my car, the mileage is better with the IPD ecu than the OEM, which I still have for comparison.

Each car was driven very gently in the granny mode to get a meaningful comparison. The 855 did have 15" wheels instead of the 16s on my car.

All the usual stuff on my car has been dealt with. Plugs, rotor, cap, wires, MAF, O2 sensors, coil, temp sensor, cleaned throttle body, you name it and it has been checked.

Any ideas on something obscure that could create this condition? I am thinking it could be something involved in the feedback to the ECU, which perhaps causes the motor to run rich. Perhaps the MAF wiring harness or the cable to the O2 sensor.

Any ideas? Thanks.