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Well I decided to do some mileage testing on my 2008 Pathfinder (V8) with all of the attention on MPG. I ran the same route for several trips to and from the Autobahn from my house. It's a 68 mile trip each way. I make this trip a lot so it's a good route for comparison and it's got a lot of mild elevation changes with the overpasses. I ran it both ways for averaging to account for prevailing winds.

My usual mileage there when I'm not concerned with economy is typically 15.5 - 16.5 at about 80 MPH with cruise control engaged, which is the typical "flow" on the Chicago expressways. I have made that run dozens of times since I bought the Pathfinder and that's a real acccurate figure.

Side note: My 2004 VW Touareg (V8) would get 15.5 MPG on a good day and it mysteriously would get better mileage the faster I ran it and even better when I towed my race car. I got 18.5 MPG one time pulling the Diasio from Indy and back at 80 MPH. Go figure!:shrug::shrug:

back to the Pathfinder....for my next test I kept it on cruise control at 70 MPH and it jumped to 18.3 which is pretty dramatic and the EPA sticker figure.

Well my curiosity got the best of me and decided to try 60 MPH and this just blew me away, I got 22.4 MPG which is ridiculous for a plus 5000 pound SUV with a V8.

I did one more test, drafting a semi at 60 MPH and yet again a big surprise. 24.5 MPG -eek--eek-:clap::clap::crazyeyes:crazyeyes

I figure that it saves me at least $4 each way and only takes an extra 10 minutes each way, pretty amazing.
 

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Shhh... Don't tell the tree-huggers or they'll be crying for reduced speed limits :). It is amazing how much of a difference the jump from 60-80mph makes in fuel economy.
 

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Faster you travel, more gas your car would consume. It's drag resistance. Most economic speed in hwy is around 55mph. Nothing new in there.
 

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Some of you don't remember the 70's Arab oil emgbargo. Interstate speed limits were reduced to 55 - to save lives. Yeah right. Don't think it can't happen again.:eek:
 

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Assuming a net zero elevation change - and that is obviously true for a round trip test - weight (or mass) has absolutely no effect on mpg while maintaining a constant speed cruise. It only has an effect during acceleration.

xtn
 

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Assuming a net zero elevation change - and that is obviously true for a round trip test - weight (or mass) has absolutely no effect on mpg while maintaining a constant speed cruise. It only has an effect during acceleration.

xtn
Not exactly, because mass is part of the rolling resistance equation.
 

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Some of you don't remember the 70's Arab oil emgbargo. Interstate speed limits were reduced to 55 - to save lives. Yeah right. Don't think it can't happen again.:eek:
I was under the impression the reduction to 55 was always about conserving gas. Of course, there was an actual supply problem then complete with gas lines and rations. Now gas is just expensive. Once the gas crunch was over, the pressure to keep the limit at 55 was driven by the Nader safety geeks.
 

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I still believe that, in the rolling hills of the east coast, 55 is NOT efficient, since 55'ers have to FLOOR IT to go up hills. Us 80mph guys can ease up on the pedal, and allow speed to bleed off. I keep my throttle pretty much just cracked the whole time.
 

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Way back when I was in college, a friend of mine drove from southwest Missouri to New Orleans in a '63 VW bug, drafting 10 feet behind semi's whenever possible. He got over 50 mpg. Not safe, but what do you expect from a college kid on his way to spring break in the big easy :D

I drove from central Missouri to central Pennsylvania in the 70's in a Honda Accord. The roads were covered with ice the entire way and I drove a constant 45 mph. I got 45 mpg. I also counted over 75 accidents, mostly jack-knifed trucks on that 1100 mile trip.

I tried drafting behind a large delivery truck once on my bicycle. I was able to maintain 45 mph on level road for over 2 miles. It was a bit ... :panic:

John Howard, former Olympic cyclist and multiple time Ironman champ set the world speed record on a bicycle... over 157 mph. He was basically riding inside a box being pulled by a race car.

Wind resistance increases as a quadratic function of speed.

Just get rid of the atmosphere and we'd all save a lot on gas :rolleyes:
 

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Some of you don't remember the 70's Arab oil emgbargo. Interstate speed limits were reduced to 55 - to save lives. Yeah right. Don't think it can't happen again.:eek:

I remember. I was working part time at a small independent gas station. People really got nasty as the price of gas went up over 40 cents/gallon. People were trying (some successfuly) to steal gas, too.
 

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SUV's are rolling wind blocks jacked way up off the ground. What did you expect? :shrug: The 5000lbs hurts the mpg on accelerating that hunk or pulling hills.
 

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Just A side note, from driving my daily driver (MB C230sport with 2.5L V6) If I drive at ~the speed limit (set with cruise control at 68mph), I get a 35mpg on a stock MB :) and im happy with my driving that nets me +5 minutes than if Im driving in a hurry at 80mph
 

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Not exactly, because mass is part of the rolling resistance equation.
True enough. I neglected that aspect because it's such a tiny, tiny contribution in most scenarios we might consider for production vehicle mileage testing.

xtn
 

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You have guts to draft a semi.
I'm not sure that it is so gutsy. Even though you can't see more than 5 feet, it is very unlikely the semi is going stop suddenly. Even if you do hit it, the speed differential will be low. Likely, you'll tap the bumper and then stop way before he does.

Also not gusty is tailgating (drafting? lol) a motorcycle, for obvious reasons.
 
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