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Save gas. Drive slow.

Q

Qacer

Platinum Member
I saw this article on CNN:
http://money.cnn.com/2008/03/2..._gas/index.htm?cnn=yes

I sent it to a friend who has lived thru the 70s. Back then, he was in the Army. This is what he said regarding the article:

During the 70's the speed limit was dropped to 55 MPH. The saving in lives and gasoline was phenomenal. The price of gas promptly dropped, the lines at the filling station shortened and the death rate on the highway was cut by at least half.

But there were a lot of pissed of fat girls who thought they were Pirelli Jones (the race car driver might have misspelled his first name) and thought that unlimited speed limits were the answer.

Oh well so much for fat girls they can afford $4.00 per gallon gas.
Click to expand...

🙂
 
Originally posted by: tenshodo13
Well, 60 mph IS the most gas efficient speed.
Click to expand...

no, its the slowest you can go in your highest gear. So it varies from car to car.

(i made that up, it makes sense to me, but i don't know shit)
 
Once you get above the 50s or so the wind resistance has more affect so gas mileage goes down exponentially.

Faster you go the worse your gas mileage gets.

Try it for a week and don't go over 55 (or whatever the speed limit is). You'll see a difference.
 
It does work, but I'd rather get a more efficient vehicle and drive 75. Corolla rental car got 36 mpg and my motorcycle gets 45 mpg freeway.
 
Originally posted by: tenshodo13
Well, 60 mph IS the most gas efficient speed.
Click to expand...

How do you figure that? I'd love to see the calculations. I know that drag increases with v (or v^2, but I forgot where the cutoff is from laminar flow). I also know that a car consumes fuel even while it is stationary.

Somewhere inbetween should be the highest efficiency

Edit: According to http://en.wikipedia.org/wiki/A...bile_drag_coefficients automobile drag is v^2 generally. You'll get to your destination more quickly at 60mph than 55mph, but you'll lose more energy along the way. Thus, I propose 60mph can't possibly be the most efficient driving speed. It must be lower.
 
Originally posted by: Eeezee
Originally posted by: tenshodo13
Well, 60 mph IS the most gas efficient speed.
Click to expand...

How do you figure that? I'd love to see the calculations
Click to expand...

numerous studies have shown that. Going from just 70-80mph is a bigger difference than you might think. I can tell the difference, but at 70mph I'm happy enough with the speed and efficiency.
 
Originally posted by: potato28
Originally posted by: Pepsi90919
i'll pay extra to drive properly....
Click to expand...

we don't even have to follow those stupid limits... 140 km/h in the left lane ftw.
Click to expand...

Trouble is you have 50 self righteous assholes camped out in the left lane driving 65mph. :|
 
Originally posted by: DEMO24
Originally posted by: Eeezee
Originally posted by: tenshodo13
Well, 60 mph IS the most gas efficient speed.
Click to expand...

How do you figure that? I'd love to see the calculations
Click to expand...

numerous studies have shown that. Going from just 70-80mph is a bigger difference than you might think. I can tell the difference, but at 70mph I'm happy enough with the speed and efficiency.
Click to expand...

Same here. 80 is definitely less efficient than 70. 75 seems to be a good compromise.
 
Drive a motorcycle, get 3x mileage 😉

My car (98 Towncar) gets about 20, while my 150 scooter/cycle/whatever you wanna call it gets ~65. I thought larger engines would get worse mileage, but I have a friend that has a 650 that also gets about 60mpg, but then again he didn't say if that was all-around or just highway. So what if he gets 40 around town, that's still 2x what most people have, and a bit better than most hybrids at a small fraction of the cost. Granted, cargo space is limited, and it won't work for a family, but for just yourself or a couple it's great.
 
Originally posted by: DEMO24
Originally posted by: Eeezee
Originally posted by: tenshodo13
Well, 60 mph IS the most gas efficient speed.
Click to expand...

How do you figure that? I'd love to see the calculations
Click to expand...

numerous studies have shown that. Going from just 70-80mph is a bigger difference than you might think. I can tell the difference, but at 70mph I'm happy enough with the speed and efficiency.
Click to expand...

Okay, great, please link me to one of these studies then.

Going from 70-80mph would have to be a huge difference in gas consumption by the v^2 drag (which screws you utterly). I'm not proposing that 60 mph is more efficient than 80 mph, I'm proposing that 60 mph is NOT as efficient as say 40mph (or a number less than 60 at least)
 
Originally posted by: Eeezee
Originally posted by: tenshodo13
Well, 60 mph IS the most gas efficient speed.
Click to expand...

How do you figure that? I'd love to see the calculations
Click to expand...

http://www.associatedcontent.c...r_car_needs_at_65.html

This article shows calculations of power usage at various speeds- Not too helpful I guess

http://auto.howstuffworks.com/question4771.htm
Average Joe's explanation of fuel efficiency

http://www.fueleconomy.gov/feg/driveHabits.shtml
Government tips - Here the graph peaks at 60.

"http://en.wikipedia.org/wiki/F...y-maximizing_behaviors
Maintaining an efficient speed is also very effective in keeping mileage up.[1] Optimal efficiency can be expected while cruising with no stops, at minimal throttle and with the transmission in the highest gear. Every car has a different optimum speed, although it is usually reported to be in the range of 35 to 55 mph[6][7] [8]. For instance a 2004 Chevrolet Impala had an optimum at 70 kph, and was within 15% of that from 45 to 95 kph (roughly 25 to 55 mph)"

So, at highway speeds, maximum fuel efficiency is around 55 mph. So i was 5 off according to this one..


 
2.4 i4..

I drive around 50-60 mph for the past 8 month.. works great.. the highway varies.. during uphills, i do not accelerate as much.. my wife never saw me drive so slow in my life... people at work zoom pass me and was laughing like crazy..

I see a lot of people with huge car launch from stop (toll lines) and flying by me. dont know how they afford gas but super is 3.99 here... 🙂

 
Originally posted by: ADDAvenger
Drive a motorcycle, get 3x mileage 😉

My car (98 Towncar) gets about 20, while my 150 scooter/cycle/whatever you wanna call it gets ~65. I thought larger engines would get worse mileage, but I have a friend that has a 650 that also gets about 60mpg, but then again he didn't say if that was all-around or just highway. So what if he gets 40 around town, that's still 2x what most people have, and a bit better than most hybrids at a small fraction of the cost. Granted, cargo space is limited, and it won't work for a family, but for just yourself or a couple it's great.
Click to expand...

Yes, dropping a few thousand pounds and significantly reducing surface area probably helps fuel economy a lot 😛
 
Originally posted by: Qacer
I saw this article on CNN:
http://money.cnn.com/2008/03/2..._gas/index.htm?cnn=yes

I sent it to a friend who has lived thru the 70s. Back then, he was in the Army. This is what he said regarding the article:

During the 70's the speed limit was dropped to 55 MPH. The saving in lives and gasoline was phenomenal. The price of gas promptly dropped, the lines at the filling station shortened and the death rate on the highway was cut by at least half.

But there were a lot of pissed of fat girls who thought they were Pirelli Jones (the race car driver might have misspelled his first name) and thought that unlimited speed limits were the answer.

Oh well so much for fat girls they can afford $4.00 per gallon gas.
Click to expand...

🙂
Click to expand...

:roll:
 
Originally posted by: tenshodo13
Originally posted by: Eeezee
Originally posted by: tenshodo13
Well, 60 mph IS the most gas efficient speed.
Click to expand...

How do you figure that? I'd love to see the calculations
Click to expand...

http://www.associatedcontent.c...r_car_needs_at_65.html

This article shows calculations of power usage at various speeds- Not too helpful I guess

http://auto.howstuffworks.com/question4771.htm
Average Joe's explanation of fuel efficiency

http://www.fueleconomy.gov/feg/driveHabits.shtml
Government tips - Here the graph peaks at 60.

"http://en.wikipedia.org/wiki/F...y-maximizing_behaviors
Maintaining an efficient speed is also very effective in keeping mileage up.[1] Optimal efficiency can be expected while cruising with no stops, at minimal throttle and with the transmission in the highest gear. Every car has a different optimum speed, although it is usually reported to be in the range of 35 to 55 mph[6][7] [8]. For instance a 2004 Chevrolet Impala had an optimum at 70 kph, and was within 15% of that from 45 to 95 kph (roughly 25 to 55 mph)"

So, at highway speeds, maximum fuel efficiency is around 55 mph. So i was 5 off according to this one..
Click to expand...

Those government tips, are they city or freeway driving? That would make a big difference. 30mph on a closed track is not the same as 30mph in the city (lots of stopping + accelerating consumes much more fuel, thereby destroying your fuel economy)

If that graph was based on a closed track, that's pretty useful information!
 
Originally posted by: Eeezee
Originally posted by: ADDAvenger
Drive a motorcycle, get 3x mileage 😉

My car (98 Towncar) gets about 20, while my 150 scooter/cycle/whatever you wanna call it gets ~65. I thought larger engines would get worse mileage, but I have a friend that has a 650 that also gets about 60mpg, but then again he didn't say if that was all-around or just highway. So what if he gets 40 around town, that's still 2x what most people have, and a bit better than most hybrids at a small fraction of the cost. Granted, cargo space is limited, and it won't work for a family, but for just yourself or a couple it's great.
Click to expand...

Yes, dropping a few thousand pounds and significantly reducing surface area probably helps fuel economy a lot 😛
Click to expand...

The best solutions are the simplest ones. Well, most of the time anyway 😛
 
Originally posted by: Eeezee
Originally posted by: tenshodo13
Originally posted by: Eeezee
Originally posted by: tenshodo13
Well, 60 mph IS the most gas efficient speed.
Click to expand...

How do you figure that? I'd love to see the calculations
Click to expand...

http://www.associatedcontent.c...r_car_needs_at_65.html

This article shows calculations of power usage at various speeds- Not too helpful I guess

http://auto.howstuffworks.com/question4771.htm
Average Joe's explanation of fuel efficiency

http://www.fueleconomy.gov/feg/driveHabits.shtml
Government tips - Here the graph peaks at 60.

"http://en.wikipedia.org/wiki/F...y-maximizing_behaviors
Maintaining an efficient speed is also very effective in keeping mileage up.[1] Optimal efficiency can be expected while cruising with no stops, at minimal throttle and with the transmission in the highest gear. Every car has a different optimum speed, although it is usually reported to be in the range of 35 to 55 mph[6][7] [8]. For instance a 2004 Chevrolet Impala had an optimum at 70 kph, and was within 15% of that from 45 to 95 kph (roughly 25 to 55 mph)"

So, at highway speeds, maximum fuel efficiency is around 55 mph. So i was 5 off according to this one..
Click to expand...

Those government tips, are they city or freeway driving? That would make a big difference. 30mph on a closed track is not the same as 30mph in the city (lots of stopping + accelerating consumes much more fuel, thereby destroying your fuel economy)

If that graph was based on a closed track, that's pretty useful information!
Click to expand...


I would assume Highway driving, as its kind of hard to go 60 mph on city streets, and the graph curve is smooth
 
Originally posted by: Kelemvor
Once you get above the 50s or so the wind resistance has more affect so gas mileage goes down exponentially.

Faster you go the worse your gas mileage gets.

Try it for a week and don't go over 55 (or whatever the speed limit is). You'll see a difference.
Click to expand...

Exactly, wind resistance increases exponentially with speed. Doing a little napkin math here, I would say it wouldn't be unreasonable to assume that wind resistance doubles going from 55 to 65. Even more so to 70, and if that doesn't make sense to you google for an image of an exponential function.

Edit: Great link

http://www.uwm.edu/~horowitz/PropulsionResistance.html
 
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