Question regarding fuel economy

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  #1  
Old 10-30-05, 07:44 PM
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Question regarding fuel economy

Given the rise in gas prices over the past year, it's been reported that a vehicle, on average, gets it's best gas mileage if you don't go over 60 mph. my question is- is the mileage the absolute BEST at 60, or simply any speed LOWER than 60? In other words, is 60 mph (or close to it) the speed at which engine performance, fuel consumption, and duration the engine is on from start to stop all line up to create a peak mileage economy?
 
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Old 10-31-05, 04:05 AM
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I would say that statement is way to general
It depends on the vehicle, engine, and gearing
I have a vehicle that get's it absolute best gas mileage at 74 mph
Another gets it's best somewhere inbetween 64-68 mph
 
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Old 10-31-05, 04:25 AM
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The key to speed vs fuel economy is the wind resistance. The faster you go, the more fuel you consume just to overcome the air resistance, but this varies widely from vehicle to vehicle. In a Corvette the difference in resistance at 35 mph or 85 mph is a lot less than, for instance, in my cab-over wrecker (which gets about 8 mpg regardless of whether I'm doing 15 mph or 65 mph, but you get the idea).
 
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Old 10-31-05, 05:27 AM
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Originally Posted by the_tow_guy
The key to speed vs fuel economy is the wind resistance. The faster you go, the more fuel you consume just to overcome the air resistance, but this varies widely from vehicle to vehicle. In a Corvette the difference in resistance at 35 mph or 85 mph is a lot less than, for instance, in my cab-over wrecker (which gets about 8 mpg regardless of whether I'm doing 15 mph or 65 mph, but you get the idea).
Hi there,
To add to the great points above, the 10% ethanol content will also change your efficiency and fuel mileage.
I have seen as high as 20% ethanol depending on the gas station and the name brand.
This should also be taken into account, given your gear ratio of your rear axle, tire quality and tread design, and if you use synthetic lubricants.
Allthebest, c4c5
 
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Old 10-31-05, 05:59 AM
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Slickshift, how do you determine that your vehicle gets it's best mileage at 74 mph?
 
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Old 10-31-05, 08:39 AM
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Originally Posted by tvshooter
Slickshift, how do you determine that your vehicle gets it's best mileage at 74 mph?
He might have used a calculater.

You can check your vehicle to find the best speed for mileage.
drive 50 mph for a tank
then drive 60mph for the next tank and so on.
 
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Old 10-31-05, 10:08 AM
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Basically yeah
Lot's of driving and record keeping
 
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Old 10-31-05, 11:40 AM
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I was going to suggest that slick obviously has no life if he has THAT much time on his hands.....
 
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Old 10-31-05, 02:55 PM
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Originally Posted by the_tow_guy
I was going to suggest that slick obviously has no life if he has THAT much time on his hands.....
lol
Well yeah, that helps too
 
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Old 10-31-05, 06:32 PM
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The gearing makes a big difference. I have an old 51 ford f1 that gets its best mileage around 40-45 mph. Much faster and the old flathead starts to wind. 16-17 mpg in town but 14-15 mpg on the open road.
 
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Old 11-03-05, 06:43 AM
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Funny, but nobody seemed to address one of the biggest influences on fuel economy, the weight of your right foot!!!! Fast, jack rabbit starts consume more gas than steady acceleration, as does using cruise control on the highway. If you are one of those people that has to be the first one off of a red light, or in normal driving is constantly on and off of the pedal, the best thing you could do is to re-evaluate your driving style. Although all of the previous replies have merit on their own, still the biggest factor in fuel economy is the driver.
 
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Old 11-03-05, 12:16 PM
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andyny02

I totally agree!! But how do I get my wife to understand that? I've been preaching to her for years about her HEAVY foot. Maybe I should quit buying her gas

About cruise control - in the 70's I hated it - my foot was steadier than the cruise control, now I hate to get on the open road without it. So has cruise gotten better or is age having a detrimental effect on me
P.S. - I'm not sure I want to know the answer.
 
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Old 11-03-05, 01:40 PM
andyny02
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Talking

Marksr,

You know, I used to hate it in the 70's as well, and agree with you that now I can't picture a long highway drive without it. As far as the question about taming your wife's heavy foot, I will have to say, (after having been married for over 18 years, and can probably count on one hand the arguments like that that I won, and still have a couple of fingers left over!!! LOL), I take the fifth!!! You ain't putting me in the middle of that one!!! I had a good friend years ago that used to annoy the heck out of me by driving like hell to get up to the speed limit, then he'd let it coast till it got to 5-10 MPH below the limit than hit it to get back up there. He bought a car from me that NEVER got less than 20 MPG, highway, and he told me something was wrong with it as he couldn't do any better than 15-17! I even switched cars with him for a couple of days, and miraclously it went back up to 20 with me driving it!!! Imagine that. I explained to him about how a steady foot will improve gas milage, but he said that was how he had always driven, so I chalked it up to the fault being either the loose nut behind the wheel, or the interface between the drivers seat and the gas pedal!!
 
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