I currenty get 15 mpg on my 4 cylnder honda Civic. I have had the oil changed, air filter checked, cylender head resurfaced, cylender head gasket replaced, spark plugs replaced, timing fixed. Compression is fine. There is no check engine light. Tire pressure is fine. No white or dark smoke coming from the exhaust. I drive mostly in city conditions at an average of 15-35 mph. The car is automatic transmission. The only thing left that I can think of that would affect the gas mileage so badly is the O2 sensors, but there is no CEL on and the mechanic says the car will not start if the O2 sensors are not working.
What could possibly be causing such horrible gas mileage?
What could possibly be causing such horrible gas mileage?