[justme1969]

Did you see the other dodge forum posts? you should have no probblem getting 22mpg if ya read what we have already done.
If you plan to tow haul good luck most big savers are defunct in that manner.
First if it needs tires already then just for the feel of it put largest used rubbers that fit on rear.
Second drive it like you have left your wallet full of cash on the top.
This should get you 16-18+ mpg alone.
The front air dam you plan is too short, need 6+ inches. {8-10 probbably}
Again read whats already been accomplished by others b4, there are several 20+ mpg dakota and durango in archives.
Last dont expect miracles with any dodge magnum or hemi engine these are all grunt engines lowering rpm will help but wont cure it. perhaps there is a cam that will allow timing adjustment and unknown by me fuel savings.