My Durango use to get about 20-24 mpg. Now I am getting 16-18. I have replaced all of the ball joints, new tires, waterpump, new airfilter and recently did a full radiator flush. I am curious as to why it has gone down so much and I want to increase the f uhh sl mileage. Would it be better to go cool air intake or chip it first?

 

Fix what is causing the lower fuel economy. How many miles on it? When's the last time it had new plugs? What climate are you in? (winter blend gasoline seems to drop fuel mileage..... yeah, I know, it's summer.... at least, it is here.....)

 

I have 155k miles and they haven't switched to winter blend yet. I put new plugs in a year ago.

 

How old are your O2 sensors?

 

I do not know how old they are. I purchase the vehical last year.

 

I'd be looking at replacing the plugs and the O2 sensors.

 

Stick with NTK or Denso for the sensors. Don't bother with bosch. You won't like the results.