i get about 23MPH mostly highway miles... I get 320miles to a tank, is that right? I just changed the plugs but it didnt help much. The car has 112000 miles on it. What else should I change? Also, the car doesnt idle high when first started and cold, it just drops to 800rpm right away.

 

ur not gonna be able to crank out any more MPG...most avengers get i think 20-25...and the 320 miles per tank, makes sense if you have a 14 gallon tank...and the 800 rpm thing, fine in my opinion, just ur car will just warm up a little slower...thats all...


but now that you mention it...i know a way to get more MPG...


lose the spare tire
roof (angle grinder)
remove the rear seats
dash
ANYTHING YOU DONT NEED

u might get like, 30 mpg at that point...o and my sarcasm isnt mean hearted, just for a laugh..

 

Change out your o2 sensors, your EGR system, fuel filter, cat converter for better gas milage, and this might sound weird but, your coolant temp sensor for the idle issue and gas milage (all of which can affect idle but that sensor has immediate influence). Also have your intake, chambers, and injectors cleaned out. Most importantly do a lot of highway driving and drive easy. That will net you better gas milage.