My girlfriend bought a 2002 Sunfire 2.2 with 32,000 miles. The gas mileage is only about 20mpg. Her old 96 Sunfire got about 32. I replaced the spark plugs, air and fuel filters and added fuel injector cleaner to the gas. So far no change. No check engine light. Anything else I could check?
Pull any trouble codes and fix. Some will not turn on the light. Then look at the live data short term and long term fuel trim and how the O2 sensors are working and tell us.
