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Is something wrong? 14 MPG HWY

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  #21  
Old 02-27-2008, 12:17 PM
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Default RE: Is something wrong? 14 MPG HWY

I'd like to see the graph but it didn't show in your post. Can you repost it?

Thanks,

Curt

P.S. I once saw a discovory channel program about internal combustion engines. Very interesting. It said that the internal combustion engine is about 60% efficiant at 55MPH in a study taken across a cross section of automobiles. Given electric motors are about 90% at best I was impressed. Beyond 55mph efficience drops off exponentially.

ORIGINAL: jmt

I do a lot of traveling for my job and sometimes I elect to take my 03. So here's my $.02.

The 4.6L is subject to extreme diminishing returns after about 3000rpm (80mph).

What I mean is, up to a certain point, ~65mph (~2400rpm), the required fuel needed to maintain that mph/rpm yields a respectable mpg. However, as the mph/rpm increases post 65mph, the added fuel consumption does not create an increase in fuel economy. It's a ratio of many factors (e.g. aerodynamics, weight, gear ratio, etc.).

Here it is in graph form:



PS: The graph is not 100% accurate and is based on my on personal highway driving.
 
  #22  
Old 02-27-2008, 01:09 PM
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Default RE: Is something wrong? 14 MPG HWY

I'm getting around 15 mpg; just under 300 miles before the light comes on. But I drive 220 miles per week commuting from home, to work, to school, to home so I'm filling up every week. With gas prices creaping up the way they are, its really beginning to hurt.
 
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Old 02-27-2008, 01:18 PM
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Default RE: Is something wrong? 14 MPG HWY

It's showing up fine for me, NWD and I'm not sure how to attach an image. It's just a simple graph I made to illustrate what I was talking about.

An average car expends 40% of its energy just pushing the air in front of it out of the way. I'd wager that a Disco requires a little bit more energy due to its box-y nature.
 
  #24  
Old 02-27-2008, 05:00 PM
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Default RE: Is something wrong? 14 MPG HWY

Well I hear its over 100$ a drum and by this summer it could be $4.00 gal$$$ that's about $96.00 a tank[:@]GOD BLESS MR BUSH
 
  #25  
Old 02-27-2008, 06:27 PM
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Default RE: Is something wrong? 14 MPG HWY

Nice graph....... It is dead on for me...... I do most of my driving on little country roads here in Southern NJ and I average about 14 to 14.8 per..... Highway is about 16 to 16.7...... When I take the travel trailer (21') and 3400 lbs fully loaded I get about 10 thru town and 10.5 to 11 on the highway.... and that is never past 65...... Not bad it is comparable with most full size pickups..... Plus I look cooler!!!!
 
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Old 02-27-2008, 08:16 PM
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Default RE: Is something wrong? 14 MPG HWY

We travel to my in-laws about once a month, 136 miles one way with 112 miles of that being all expressway and the rest being country roads.
We did a experiment, we fill up and tried to drive 80 mph while on the expressway and 65 on the county roads. We averaged 72mph for the whole trip (round trip) and used 23 gals of gas.
Next month same trip but set the cruise at 65mph, averaged 64mph and used 13 gals of gas.
At the current price of $3.39 per gal we saved $33.90.
Driving 65 added 30 min round trip, that equals $67.80 per hour, so you are right, time is money.
I have driven a million miles (literaly) and most of them have been at 65, it is relaxing, safe and efficient.
Life is short, sit back and enjoy the ride.
And yes DI's do get better mpg than DII's, not even God knows why.
 
  #27  
Old 02-27-2008, 09:32 PM
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Default RE: Is something wrong? 14 MPG HWY

Some on here say that you need to change o2 sensors at certain intervals for better mpg. If the sensors were not doing the proper job, wouldn't you get a CE light?
 
  #28  
Old 02-27-2008, 10:52 PM
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Default RE: Is something wrong? 14 MPG HWY

As with any sensor, there is a tolerance level so the values can decrease and decrease while still remaining in the 'good' range. Also with progressive learning from the ecu, if other sensors equal out the low O2 sensor issue, it could level out and not trip a SES light.

But yes with time, the O2 sensor loses efficiency and will decrease your engine's mpg. Not sure how often is the 'optimal' replacement time to maintain the best efficiency though
 
  #29  
Old 02-28-2008, 10:25 AM
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Default RE: Is something wrong? 14 MPG HWY

From what I have been told is 65mph is the best speed
to get the best mpg,, this is for a Disco I, I think the Disco II
would be the same or within 5mph.

But the faster you go the less time you are using gas so
time per gallon is less (TPG) but MPG are less.
If you have to use ethanol that isBAD for MPG.
 
  #30  
Old 02-28-2008, 11:29 AM
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Default RE: Is something wrong? 14 MPG HWY

I wonder if you should like every 6,000 miles remove the o2 sensor's and wipe off with alchahol? or is that a bad idea?
 


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