Dodge Dakota R/T
 

Per on board systems vehicle placed 8mpg avg. "it does not tell city v/s hiway". I couldnt afford to drive it any longer as fuel hit $4 a gallon.
I found the overdrive in these vehicles slips in even the best of situations.
Typical failure issue, bought a mega viper rebuild system, Tried 2x to get it together rite and then took it to a pro. who found drum pressure seal with lip in not out. set shift and lock up to street and strip to reduce slippage in shifts. installed 3500 stahl converter.
Results 11.5 mpg.
Swapped 8 into 1 pipe, with single 4" flowmaster, result nothing positive as I became amused with the sound now not fuel savings.
Replaced tires and wheels to lighter weight, with lower sidewall height but larger circumfrence and gained 1mpg.
Tried air pressure adjustments but seen no noticable change. Removed water pump and direct driven fan, bought new water pump and bored 3/8" holes in driving face of impeller. :D" old circle track car power adder trick". Then installed fan clutch, and also Hole sawn 1.75" into aftermarket junkyard aluminum fan blades.:D;) "also circle track car power adder.
Result 13.8 mpg.
This was as far as ive gotten, Due to my Lemon 02 civic failing on the Hiway.
I will never get another Honda! So for now I have to drive the old Kia that the Civic supposedly replaced.
The fuel mileage increases were multi purpose as Im sure you have guessed, For every fuel economy gain there is an equivellent performance gain, It is my play toy but now I can afford to drive it again.
It has been long due for tune up so that would also probbably net in combination with tire pressure a .5 or so increase.
Water pump fins and fan blades are normally designed for maximum flow.
This vehicle as most do doesnt need it, but to sell a warantied vehicle automakers aproach will always lean to overdone and underpowered unless it is a truck.

What does the 3/8" hole in the impeller do? Doesn't seem significant enough to result in any measurable fuel economy improvement.

less internal drag. Mount a pump on sheetmetal or such and put your 1/2" drill on it, see how fast the drill burns up when circulating water back into a buckett with it.
This hydraulic pump does not lessen its hp drag much in correspondence with rpm. We would actually trim the impellers on race car our car actually cooled better with the reduced flow. I still dont have underdriven pulleys yet they will make even more energy savings.

A belt driven fan delete is usually good for 2 MPG and some times a much as 4 MPG.

How about rear gearing? (assuming it's a 2WD)
Stock, I believe, is 3.92. Can you swap to a 3.55 ratio?

I think I understand the why, but I'm having a hard time picturing where you drilled the holes.
Dakota R/T--360? You might try some of the aero mods I've done. I'll load up a couple pix to the garage...

Yes rear gear is next it now has more torque and power so stepping down from 4.11 rear gear to 3.73 or 3.55 will be good no sense wasting rubber burning tires and such when I can jump fuel econo up to 17mpg or better. I think at the end this should have very high street rod performance numbers much better than stock and 2x-3x OEM fuel economy.
But first must get economy car fixed or purchased that is hitting high 40 mpg numbers.
Ive gotta have my daily driver...

continued.. Yes there are lots of things to do to improve this truck, dropping ride height, ground fx., rear gear, turbo, but all must await my daily driver.

hahaha I found it lol see been there did that Dakota R/T is gas sucking pig nomatter what the attempt. sure is fun to beat upon though.