: The M6, S38B35 does not have an engine check light. Therefore, it is very possible for the Motronic to be runnung open-loop which would cause poor gas milage. I suggest taking a digital volt meter and measuring pin 5 on the Diagnostic Connector (pin 12 of DME) and make sure the voltage is cycling 0V to 12v on a period of 1-2 seconds at idle. This is the diagnostic for the O2 sensor function. Should you find yours at a steady state at near 0v or 12v your O2 sensor may have failed or the AFM CO needs to be adjusted.