Decreasing MPG?

[Vladiso]

I have a little display that is set to show miles per gallon in my I35. Over past few months the number has been decreasing. Im wondering if it is a sign of something serious. Originally, the car showerd 21 mpg and now its down to 14.2 mpg. Should I look into it or simply ignore it like i have been ?

[marlin29311]

Are you keeping up with your regular maintenence (ie, changing oil, filters, etc...)?

Have you changed your driving style at all? Do you gun it, or are you an easy driver?

[jongier]

Yeah I mean how much time has gone by, has it gradually changed over time or did you just wake up one day and your ride decided to fall off the wagon?

[Amosnorider]

Check air filters, any air or fuel sensors(oxygen sensor mass air flow sensor), tire pressure and alignment. Going from 21 to 14 is pretty drastic. i can get that MPG in my Ford Explorer. I get 28 MPG on the highway in my 2000 I30. also: steady accel and staying off the brake can boost MPG dramatically. I got over 21 MPG in my Explorer from 15 MPG just by changing my driving habbits.

[maxhopper]

Also be sure to check for any vacuum leaks around the intake manifold.

[Vladiso]

thank you guys very much.i have not changed my driving style or type of gas im using (even the gas station is the same). the mpg drop happened over the course of 4 months. Im probably a little overdue for maintenance.

[lightsout]

this might sound odd, but smell your exhaust quickly while the engine is running...if it smells a little like Gas, i would go with MAF or 02 sensors.

no check engine light?Does it idle normal?