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2003-2009 Nissan 350Z

Significantly better gas mileage with A/C on, and windows up

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Old Aug 21, 2009 | 09:32 AM
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Default Significantly better gas mileage with A/C on, and windows up

I always thought the gain was pretty minimal with the windows up and A/C on compared to just having the windows down, but lately I have seen a huge difference.

I usually drive with my windows down mainly around town and on short highway trips of 10 miles or so. I've gotten deceint milage, buy for the past 2 weeks I have been driving windows up with A/C and I swear my fuel needle is going down a lot slower.

Maybe its just a mental thing, the computer usually reads only 1 or 2 mpg difference. I wonder how much drag having the windows open in a 2 door coupe like the Z exibits compared to a sedan.
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Old Aug 21, 2009 | 09:54 AM
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very scientific, I'm sold!

I just read an article last week about "driving green".

Basically it said "most cars" get better milage under 45 mph with the AC off. Above 45 mpg, roll up the windows and turn on the A/C.
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Old Aug 21, 2009 | 10:00 AM
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Its states this in our manual that it MIGHT be better to roll your windows on the highway...

Well at least in my NISMO manual...
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Old Aug 21, 2009 | 10:18 AM
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Originally Posted by only350z
Its states this in our manual that it MIGHT be better to roll your windows on the highway...

Well at least in my NISMO manual...
I would agree with that. Seems like the 350's design doesnt drag too bad at 45 mph. 55 or so it seems to start chopping (highway speed). I have been paying attention to wind drag ever since I read that article
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Old Aug 21, 2009 | 10:34 AM
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I'm getting 27.5 mpg going 70mph on the freeway, windows up and A/C on
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Old Aug 21, 2009 | 11:28 AM
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Honestly I think my gas mileage is worse with the windows down at slower speeds simply because I can hear the car better. I shift later to revel in the glorious sound.
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Old Aug 21, 2009 | 01:01 PM
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^^
I'm with you on that one...my MPGs went down by about 3-4 when I installed my JWT popcharger mainly because I wanted to be at WOT more just to hear the motor (that was about a year ago, and now I've gotten used to it calmed back down on my driving and my MPG is actually about .5 higher than pre-install which is also prob due to driving style and not the popcharger)
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Old Aug 21, 2009 | 01:30 PM
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hmm i get 32mpg on the intersate with 19" wheels haha
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Old Aug 21, 2009 | 01:48 PM
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Originally Posted by Glock-Star
hmm i get 32mpg on the intersate with 19" wheels haha
did you recalibrate the speed sensor so it's accurately presenting the mph? If not then a larger tire will display a higher mpg but wont' actually get it.


Mythbusters already proved that windows up with a/c on does improve mpg over windows down at city and highway driving. It was a pretty interesting episode.
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Old Aug 21, 2009 | 02:29 PM
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Originally Posted by binder

Mythbusters already proved that windows up with a/c on does improve mpg over windows down at city and highway driving. It was a pretty interesting episode.
I dont understand how low speeds with the windows down could cause worse milage than with the A/C on... Did it explain it in the episode? I guess there is more air resistance than I realize?
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Old Aug 21, 2009 | 04:01 PM
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it explained it in the issue. everything was controlled on a circular track and he had to stay at a certain average speed.

i'm pretty sure you could find the clip of it online somewhere.

Now, the differences were small. They measured out mpg to the hundreds and it was only around 1mpg different but that still breaks teh myth or whatever. a difference is a difference.
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Old Aug 21, 2009 | 05:33 PM
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Originally Posted by Zian
Honestly I think my gas mileage is worse with the windows down at slower speeds simply because I can hear the car better. I shift later to revel in the glorious sound.
Touche. On another note, I am going enjoy this next decade or less of internal combustion, gasoline burning, no camera's on the highways and traffic lights (mostly), no mpg restrictions (will depend on future laws), and stick-shifting.

For all it is worth before BIG brother spoils the fun. Conservation methods are inevitable and I will sure be one to remember these days of enjoying my Z and any other sports cars that follows to its max.

p.s. I love hearing my Z scream every safe chance I get.
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Old Aug 22, 2009 | 06:42 AM
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Originally Posted by whitenoiz
i would agree with that. Seems like the 350's design doesnt drag too bad at 45 mph. 55 or so it seems to start chopping (highway speed). I have been paying attention to wind drag ever since i read that article
can you post the article your refering to please im intrested in reading
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Old Aug 22, 2009 | 11:56 AM
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Originally Posted by Glock-Star
hmm i get 32mpg on the intersate with 19" wheels haha
In your Honda???
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