My 2008 mistubishi outlander arround 24 000 km ( 15 000 mile ) and for some reason it suck a lot more gaz than usualy.
Normaly i can drive from my home to work and have 8.5 to 9 l/100 km ( dont know the convertion mpg),
now i got arround 14 to 16 l/100 km.
I also have a nother point, i when to the dealer last time i change my oil ( i alway go to dealer), and they change my air filter, now when i accelerate, my engine dont sound the same at all, but at the beginning my car did not suck that ammount of gaz, even with the new air filter.

 

Did the bad mileage start after they changed the filer, they may not have put it in correctly, check to see if the filter box is secure, if they created an air leak around the filter that could seriously affect the mileage.

 

i did realise it when they change the air filter, i dont feel any air leek too.

 

.. will it be a big factor for having a reverse filter???

...

 

This is gonna sound weird but, ever since I put A K&N drop in filter and been using mid grade gas im getting way more mpg, I always keep track of my mpg.