Poor Fuel Economy

Definition: Fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, economy is noticeably lower than it was on this car at one time, as previously shown by an actual road test.

POSSIBLE CAUSE ACTION

Dirty air filter Clean or replace

Fuel Injected Check air/fuel ratio, (O2 Sensor Voltage)
perform injector balance test,
(check vacuum line and return hose),
check fuel pressure

Speedometer inaccurate Check speedometer calibration