[jrecken]

I have a 99 Buick Century with the same engine. I keep track of every drop of gas I put in the car and record the mileage every time. In the cold weather my mileage drops to 22-24 mpg. A month ago I filled up and the mileage dropped to what you mentioned. I filled a second time at the same gas station from the same pump and again the mileage was way down to 14-15 mpg. I was on a trip at the time and I was beginning to think something was wrong with the car although it was running just fine. I filled up again at a different gas station and the mileage went back to normal. I can only believe that it was just bad gas.