Gas Milage question.......

[LWM]

Do you know if a CAI and/or exhaust will improve mpg on a 3.7L?

Yes they will! But the question is by how much and how long will it take you to recover the expense.

A CAI will give you more air intake and the exhause will move it out quicker, this effect is known to increase the mileage. The problem is that you will only pick up maybe 1 MPG if you are lucky and it will cost you an estimated $400 give or take to gain that 1 MPG. I will leave it too the math majors to determine how many miles it would take to recover the expense.

[IamJEEP]

O.k., now I'm really confused.........After I had reset my average mpg I was reading 17mpg city, I was stoked. But, lately I've been reading from 12mpg-13.5mpg, wtf? I havn't done anything different, same gas, same style of driving, no long trips, average of 60mph..........................What gives?

[strokeZ]

What was the ambient temperature? I have found that the 4.7L really becomes inefficient somewhere around 90 deg F. Below that temp I can usually get 17 to 18 on the highway (flat few hills) but above that it drops to between 14 and 15 mpg. I live in the Houston area so its also quite humid, which does not help.

[IamJEEP]

What was the ambient temperature? I have found that the 4.7L really becomes inefficient somewhere around 90 deg F. Below that temp I can usually get 17 to 18 on the highway (flat few hills) but above that it drops to between 14 and 15 mpg. I live in the Houston area so its also quite humid, which does not help.

It's been 85 to 95 degrees here, feels like 100 with the humidity.

Yesterday I took a 20 mile drive at 60mph and averaged 23mpg. When I got into town, stop and go trafic, I was averaging 16-18mpg. Same gas 87 octane, 35psi in the tires as recommended by door sticker, 89 deg outside, Ño wind and flat land.

Is there a "proper" way to reset your mpg reading? Should I do it while driving or before I start to drive?

[LWM]

Is there a "proper" way to reset your mpg reading? Should I do it while driving or before I start to drive?

Both of these will have the same effect, if you reset before you start driving you will have that 1 mile where you used more fuel to get up to speed but the rest will quickly adjust to make up for that little bit of extra fuel. I say just push the button, you will get the most acurate at the moment reading possible.

[Doc in AZ]

my wife drives a nissan and the computer gives an instant fuel economy as well as a long term.

while displaying in the instant mode when you floor it the reading is single digits, when you let off and coast it goes up to 60mpg.

if you display the long term it will give you the average since the last reset. the longer you drive between resetting it the more accurate "average" you will get. if you reset it every 10 minutes you can maniuplate and MPG you want.

[IamJEEP]

my wife drives a nissan and the computer gives an instant fuel economy as well as a long term.

while displaying in the instant mode when you floor it the reading is single digits, when you let off and coast it goes up to 60mpg.

if you display the long term it will give you the average since the last reset. the longer you drive between resetting it the more accurate "average" you will get. if you reset it every 10 minutes you can maniuplate and MPG you want.

I usually reset between fill-ups.

I've been getting 22mpg highway and 12mpg city. Is it supposed to be that much of a spread?