Poor Fuel Mileage

WARNING: This page is about a different car, the 2002 Isuzu Trooper, 2002 Isuzu Rodeo Sport, 2002 Isuzu Rodeo, 2002 Isuzu Axiom, and 2002 Honda Passport. However, it is still accessible from the selected car via links, so may be relevant.

Perform On-Board Diagnostic II System Check.
Perform Electronic Throttle Control (ETC) System Check.
Check fuel pressure.
Check vacuum hoses.
Check ignition timing.
Check spark plugs.
Check for correct tire pressure, vehicle carrying heavy loads or poor driving habits.
Check if A/C is on all the time.
Check for restricted air filter.
Check for restricted exhaust system.
Check for proper speedometer calibration.
Check EGR system.
Check oxygen sensor for silicone or lead contamination.
Check engine compression.
Check for dragging brakes.
Check gasoline quality and quantity.
Check for cooling system running too hot or cold.
Check for faulty thermostat.
Check for faulty Torque Converter Clutch (TCC).
Check for leaks is air intake system and crankcase.