I absolutely love my 2009 Jeep (32K miles) with the only thing i don't love is the MPG (typical). So, I've been doing all I can to improve the mileage.
So far, I've:
- added a K&N air drop in filter (this gave the greatest improvement)
- installed a MBRP offroad exhaust (mild MPG improvement; with way more grunt and definitely louder... still cant tell if its too Ricey... but its growing on me)
- Synthetic Oil (mobile 1... will try Royal purple next time)
- Synthetic gear oil in the differentials (Royal Purple 75w90)
- Changed my driving habits (no more gunning it from a stop.... and now I coast to a stop)

So far, I'm up to about 19MPG city 25HWY

Where I need advice on is future upgrades (are they worth it)....
- Changing the ATF to royal purple
- Changing the transfer case fluid to royal purple
- adding a transmission cooler
- changing the coolant to engine ice (or what ever is rated best)
- AEV heat reduction hood (mostly for sucking in cool outside air)

My goal is to get somewhere between 21-23 MPG city... if all above wont get me there let me know... Most important let me know which of the 5 future mods are worth the effort.

Thanks.

 

Get rid of unnecessary wight. If u don't use the back seat, pull it! These mods are FREE and work best!

 

Adding a chip such as super chip won't improve mileage? My future add ons are getting my jeep chipped and possibly a new muffler.

Also heard good things about getting a better throttle spacer as well.

 

20 mpg city is a tall task. Are those hand calced numbers or what the dash says? All these mpg improvements really are a little trumped by the fact that we drive a square flat grill, flat windshield jeep, with no aerodynamics. My opinion, the possible gas savings will never really match the money you put into all that stuff. But I could be wrong

 

Besides Aerodynamic improvements to the body. The best bang for your buck is to drop rotating mass. This means a lighter wheels, Tires, rotors, flywheel, and driveshafts. Dropping 20lbs of rotational mass is the equivalent of dropping 100 lbs of dead weight "Non Rotating mass"

Dropping rotating mass has been around since the beginning of Race cars. Just with a lighter wheel and tire combo I was able to increase my 2012 Mazda 6's fuel economy from 26mpg to 31 mpg by going from a 19lb Wheel to a 12 lb wheel and from 52 lb tires to 43 lb tires.

Thats a total of 16lbs per corner X5 = 80lbs X4 = 320lbs of dead weight.

Here is a hotrod article on weight reduction for ideas

Weight Reduction - How To - Hot Rod Magazine

 

I applaud your your effort, but how could an air filter improve MPG?

All that a replacement air filter can do, other than filter the air, is have more or less pressure drop across it. In part throttle operation there will be a given absolute pressure in the intake manifold that will determine the air flow, and with a constant fuel/air ratio (trimmed with feedback from the exhaust O2 sensors) the fuel flow is fixed in ratio to the air flow regardless of the air filter pressure drop. There is pressure drop across the throttle body and pressure drop across the air filter -- If the filter is more restrictive, they'll be a bit more across the filter and a bit less across the throttle body -- End result is the same total pressure drop, and zero change in efficiency.

A couple side notes:
A less restrictive air filter will make more power at full throttle and high RPM. With the throttle open fully, all of the pressure drop is across the air filter (plus the intake system). The filter's pressure drop restricts air flow, and thus fuel flow for a given A/F ratio, as well as adds some pumping losses. But to put it perspective, I have a filter minder that records the pressure drop across the air filter in the Jeep. It recoded a max of 10" water (0.36 PSI), which is about the same effect as the difference between sea-level to 700 feet altitude. In racing that makes a difference, but most people can't notice the difference in power with only a 700' change in altitude.

Edit regarding Diesel engines: Filter pressure drop does affect the MPG (efficiency) of a diesel engine -- Because it has no throttle for the air, any reduction in the pressure drop across the intake increases the pressure on the piston during the intake stroke. In other words, increasing vacuum on the top of the piston during the intake stroke takes more power (commonly called pumping losses).

But with our gasoline engine, these pumping losses at partial throttle are determined by the intake manifold absolute pressure (vacuum), not by any pressure drop across an air filter. For example, with constant conditions, and the cruise control set at 60 MPH, there would be a constant air and fuel flow. Now take out the air filter completely -- Manifold pressure would rise very slightly, air flow increases, fuel flow increases, more power would be developed, engine RPM would rise slightly, then the cruise control (presuming it is sensitive enough) would close the throttle slightly, the intake manifold pressure, air flow & fuel flow would decrease to exactly where they were with the air filter in place. The pumping losses are exactly the same because the manifold absolute pressure is exactly the same.

The reverse, clogging the air filter, doesn't affect MPG either -- for the exact same reason. If you were to duct-tape the stock air filter so it's only 1/2 exposed, you'll loose top-end power (and perhaps collapse the filter if you give it full throttle); but if you reset the MPG while driving flat ground on cruise, you'll see the exact same MPG as with a clean/new K&N filter.

 

Are you running the hard top or soft top? Weight savings to be had there also, depending on what you have.

 

For all the money that you could potentially spend to up your mpg lets say 3 mpg how long is it going to take to recoup on that money. If you spend lets say $1000 to pick up 3 mpg it is going to take quite a few trips to the gas pump to recoup on those numbers. To me it just seems like in that instance your stepping over dollars to pick up dimes. Why not just deal with the gas mileage you are getting and put that money into something else in the Jeep? I mean these things have the aerodynamics of a brick and you have only make the powertrain so efficient.

 

Dude, if you're getting 19 city and 25 highway you should be stoked! The only way you're going to increase your gas mileage more is to get a new vehicle. I'd shit myself if I got that kind of gas mileage.

 

I know if I got over 20 mpg I would be stoked. I get 15 city and 20 on state roads that have speeds 55 and below. Interstate mpg is around 17 because of the speeds above 55 mph.