2006 Pontiac Grand Prix Mileage Steadlily Decreasing

2006 PONTIAC GRAND PRIX
40,095 MILES • 6 CYL • FWD • AUTOMATIC
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JKIMMEY914
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  • 1 POST
I was wondering what might be causing this. I get my oil changed every 3,000 miles. I keep track of my mileage per gallon with my trip A monitor and I have noticed about a 40 mile difference per tank. I had been getting about 420 miles per tank (16 Gallon), Now I get about 40 less and it seems like It has been decreasing steadily ,I wanted to get it looked at soon,but I wanted to ask someone that knew the business. I wasn't sure what would affect that Fuel filter,air filters etc. I am not sure.
Thanks guys Please reply soon..
Dec 14, 2007 at 8:23 PM
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DENNYP
  • CERTIFIED EXPERT
  • 1,824 POSTS
yes, the filters will affect fuel economy. Weather conditions,road conditions,driving habits,and tire wear will also affect fuel economy. I would recommend finding the average fuel economy over 4 tanks of fuel and see what your economy estimate is.

example: 300miles/16gallons=18.75mpg
325miles/16gallons=20.31mpg
275miles/17gallons=16.18mpg
295miles/16.58gallons=17.79mpg

Total economy=73.03/4=18.26mpg
Dec 15, 2007 at 11:10 AM