If your car has been driven just over 30,000 miles, it's time to replace the spark plugs. Over time, spark plugs can become covered in carbon deposits, which make them work harder and decrease your car's overall fuel efficiency. When your car misfires (when the engine stops for a brief second then picks up again), it's a sure sign your spark plugs need replacing. Misfires increase exhaust emissions, which can affect your car's fuel efficiency as well.
ANDREWS MCMEEL SYNDICATION