Jeep Commander Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
31 Posts
Discussion Starter #1
I am looking at all ways to improve my MPG (2006 5.7). I have read many claims that an after market exhaust system combined with a CAI will get me 1-2 MPG. From those that have done it what is the actual measured impact if any. Please try to respond with the facts as I don't want to waste money. thanks guys.
 

·
Registered
Joined
·
417 Posts
The facts are this: do the math when considering expensive add-ons only for fuel savings. It's called and ROI (return on on investment) analysis.

Basically, it will take you a certain amount of time to make up for the expense of buying the performance equipment that may (or may not) get you better mileage. Keeping in mind that when you put go-fast parts on your car, your tendency will be to try them out - negating any savings you were expecting.

Intake, exhaust and programmer are the most popular bolt-ons that help your engine work more efficiently. Let's say they cost you $1000 and they save you 1 mpg.

At $4 per gallon of gas and going from an average of 12 mpg to 13 mpg and driving an average of 1000 miles per month:

$4 per gal @12mpg for 1000 miles per month = 83.33 gal
$4 per gal @13mpg for 1000 miles per month = 76.92 gal

A difference of 6 gallons per month

6 gallons x $4 = $24 per month savings

Initial investment ($1000) / $24 month = 41.66 months to recoup your initial investment.

Then there's the free way. Keep your tires inflated, your vehicle serviced, lighten your load and drive like a grandma. You'll probably still see the 1 mpg (or more) improvement.


I am now stepping down off my soap box.

 

·
Registered
Joined
·
1,128 Posts
How many miles are on your XK? Given the model year I'm sure you're due (or over due) for spark plugs. They're supposed to be replaced every 30k miles.

I saw a 3mpg improvement when I put fresh plugs in. (I'm also fairly certain that the previous owner only used mine for city driving, so it was a hard 24k miles when they owned it).

So if you haven't had it done..... fresh plugs, new tcase and diff fluids are due and will definitely help out with MPG.

If you are up to date with maintenance, don't buy an intake for gas mileage.......unless that's just the excuse you're using so your wife lets you.
 

·
Registered
Joined
·
31 Posts
Discussion Starter #4
Soapbox

Your statements are accepted and understood.

What I am looking for is better range and the money does not matter that much as long as it makes a 1-2mpg improvement.

You see in Africa we can be 100's of miles away from fuel and there is only so much you can carry given I already need 2 spares etc etc etc.

Even 1 extra mpg*40 gallon's can mean the difference between walking though the bush for 40 miles to get fuel (and maybe getting eaten - no joke) or not.

thanks for your input.

:)
 

·
Registered
Joined
·
1,128 Posts
Lol well that does change perspective a bit!

Here's what I recommend:
1) make sure you're up to date on maintenance.
2) get a programmer like supechips and run the efficiency tune.
3) get a set of good LRR Rated tires (low rolling resistance). If you can't get LRR tires, get a standard tread design and target lighter weight.
 

·
Registered
Joined
·
31 Posts
Discussion Starter #6
Agreed

Got the superchips, got the correct oil. Tyres are OK but off road often have to deflate anyway. Looking for a bit more thats all. I don't want to go down the CAI and exhaust path only to have it make no difference.

thanks again
 

·
Registered
Joined
·
417 Posts
You say you have 40 gallons. Where is that coming from? The only for sure way to get better range (I would not feel safe doing the 1 mpg thing) is to hold more fuel. Most do it with Jerry cans (or 4 as mentioned above) Some have put spare tanks adding 30 gallons. Of course, that fits in the spare wheel well and subtracts one place for one of your spare tires to fit.
 

·
Registered
Joined
·
31 Posts
Discussion Starter #9
Plugs & Fuel

Yes I am overdue for plugs. Stealer would not do it at the last service even though it is due. Re fuel - I carry Jerry cans and there is a limit to what I can handle with all the other stuff. Thanks for the feedback. Does anyone have a measured impact of exhaust and CAI?

cheers
 

·
Super Moderator
Joined
·
14,914 Posts

·
Registered
Joined
·
31 Posts
Discussion Starter #11
Kind of figured that

Thanks for your input. I suspected that I would be wasting my time and only be disappointed.
 

·
Registered
Joined
·
1 Posts
if you replace your stock filter with a drop in k&n you should see about 2-3mpg thats about what i got and you said you are over due on plugs so you get 1-3mpg so you should pick up avg. of 3mpg should cost bout 100 bucks or so plugs costing the most pending on brand good luck out there
 
1 - 12 of 12 Posts
Top