Oh my gosh! My girlfriend's car has been a nightmare! :banghead: Over the past few months it has lost a large amount of gas mileage, it dropped to about 15 MPG. Any clues???? Air filter is fine. Also, any clues on how to access the the rear spark plugs?

Unless the car has upwards of 70,000 miles on it or has drivability issues the spark plugs should be fine. Oxygen sensors can cause poor gas milege. Also make sure the car warms up to operating temp when it is drivin around. If it stays overly cold, you may have other problems. Do you have a service engine light on?

the car has about 99k on it, there is no service engine light and the operating temp is normal

Im having similar problems... I was averaging 22mpg all the time, and im down to 17mpg!!! Besides o2 sensors anything else? (i have 137,000 on my 99)

check the fuel filter/ fuel lines, run some injector cleaner as well

I'd change the o2 sensors(both front and rear)fuel filter,and Throttle body cleaning.Or if you can't diy,take it to a shop and get a fuel system cleaning.