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-   -   First Tank MPG (my story), would like to hear yours (http://www.jeepgarage.org/f73/first-tank-mpg-my-story-would-like-to-hear-yours-30112.html)

felipito 10-25-2011 10:40 AM

First Tank MPG (my story), would like to hear yours
 
Dear fellow WK2 users, here is my story.

I received my new WK2 Overland V6 with black Interior, i added the front tow hooks and all the skid plates.
When i received it from the dealer it had 13 miles on it and when i first filled up the tank it had 20 miles on it. I filled her up to the top, it got 20.5 gallons (the gas light was not on).
Ok so i got my advice's on how to treat a new engine and a good or correct break in engine, and i drove almost like a grandma with some sporadically good acceleration and some full throttles as well.
When the jeep had 60 miles on it (all city driving) i went to the beach and back on a beautiful sunday (Dominican Republic beaches.....which are incomparable), the trip was about 90 miles going and back (45 miles x 2). The evic said i was avg. 9.3l/100 km which is
25 miles per gallon (at 65-70 speed). At this time i am thinking this is the best vehicle in the world!!!! so next i keep it for another 60 miles in the city, a lot of SHORT trips and lot of traffic and red lights.
I then again decided to go to the beach again the next Sunday and drove the same 90 miles total (45 back and forth) .
At this time when i turned on the car the low fuel was on and i when to fill her up.
It had 330 miles total less the 20 miles it had before the first tank, totaled 310 miles and the gas pump said 23.3 gallons.
Average miles per gallon was 13.5
One of my question are; how is it that for more than 60% of highway use and 40% city driving my MPG is so low?
I also read people saying that the first tanks are always lower MPG because of the break in engine, etc.
I just want to know if your first tanks and until when did you see increases in your MPG.
Or mine will stay like this forever?

After how many miles on the odometer do you think (if it is true) that i will get better MPG?

Please give me your opinions,
It can be of V6 or V8 Users

Cherodude 10-25-2011 07:42 PM

Re: First Tank MPG (my story), would like to hear yours
 
I have kept mileage calculations for every tankful in my vehicles for over 35 years. The effect of a new engine is highly overrated when I look at those records; but maybe there is a small effect in the first 1000 miles or so.

Far more significant effects are air temperature, wind direction, whether the A/C and other high power draw accessories are running, rain or snow on the road, tire inflation, flat vs. hilly terrain, trailering, etc. Any one tankful can be off the normal range for so many reasons. I'd say continue your break-in and see how it looks after four or five tankfuls.

One thing I have seen from my own calcs though: driving faster on the highway does not have as much real-world effect on my mileage as some pundits say. They never seem to factor in that when I am going a faster speed, or course I am using more gas, but I'm also going a further distance in the same time, plus the engine may be working in a sweeter spot of its power curve. etc. My Jeeps have usually had their best full-tank highway mileage at about 70mph, rather than 50.

bond7 10-26-2011 09:25 AM

Re: First Tank MPG (my story), would like to hear yours
 
I got just about 350 miles out of the first tank of gas on my V6 Laredo 4x4

Hemidog 10-26-2011 11:24 AM

Re: First Tank MPG (my story), would like to hear yours
 
You should calculate your mileage manually for your trip if you want the true MPG. I have noticed that the computer in the Jeep doesn't give you a true average of based on the miles traveled between resetting the average mpg. For example, in my Vette, I can have several thousand miles worth of mpg data and to get it to move the average 1 mpg takes a hard flogging for several miles. In the Jeep I can average 20 mpg for 40 miles after a reset, then floor it for the last .5 mile and tank the average in the ground. It just seems like the Jeep is basing the average on the last 200 miles or so. Not sure what data pool is limited to, but it definitely isn't the total between resetting the average mpg counter.

felipito 10-26-2011 07:19 PM

Re: First Tank MPG (my story), would like to hear yours
 
Quote:

Originally Posted by bond7 (Post 504276)
I got just about 350 miles out of the first tank of gas on my V6 Laredo 4x4

How much gas did you placed in?
also i always had the A/C on.....how about you?

about the mpg average i dont care about it, i prefer to watch the bar consuming chart that the jeep has when i am in highway because in the city it goes up to much and only goes down when i stop at a light.

netcoolery 10-27-2011 02:18 PM

Re: First Tank MPG (my story), would like to hear yours
 
Quote:

Originally Posted by Cherodude (Post 504020)
One thing I have seen from my own calcs though: driving faster on the highway does not have as much real-world effect on my mileage as some pundits say. They never seem to factor in that when I am going a faster speed, or course I am using more gas, but I'm also going a further distance in the same time, plus the engine may be working in a sweeter spot of its power curve. etc. My Jeeps have usually had their best full-tank highway mileage at about 70mph, rather than 50.

Yep - your engine is working at a sweeter spot. 70 Mph is a little high to see this, but I've often seen better mpg in the 60s with some vehicles.

What eventually gets you though, is the air resistance. Drag goes as the square of your velocity, so the air resistance at 60 Mph is four times what it is at 30 Mph.

Modern vehicles, with their superior aerodynamics have been able to push up that "crossover" spot (where the efficiencies from the engine/gearing at speed are overcome by the inefficiencies of the increased drag) but at some point the drag wins. Nobody gets better mpg at 80.


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