If your car has been driven over 30,000 miles, it's time to replace the spark plugs. Over time, spark plugs can become covered in carbon deposits; this makes them work harder and decreases your car's overall fuel efficiency. If your car misfires (the engine stops for a brief second then keeps going), it's a sure sign your spark plugs need replacing. Misfires increase exhaust emissions, which can impact your miles per gallon as well.
ANDREWS MCMEEL SYNDICATION