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While I am normally an advocate for mass transport and bleeding-edge high technology, I do like cars all the same. But, I live in the United States, where "car" also means "pick up truck" or "tank", and you can get a hybrid version of a Yukon XL. You know, in case you want to love the environment with your fists.

So when I see an article about the Peugeot 208 GTi, and read that it gets 74-83mpg, I'm not only pissed off that I can't get that over here, I also know that a car like this wouldn't be as popular as a Suburban, or an F-150, or a Fusion. Especially with that [awesome] purple paint job.

I can't help but mention how ridiculous it is that we're all driving fossil fuel-powered personal vehicles as our primary method of transportation, but the fact that the US's fleet gets an "impressive" 32mpg is just insanity. Clearly we are more than capable of producing way better than what we have, so why aren't we? Is it really that Americans "like" huge, tanky cars and SUVs like Suburbans and Challengers? Or is it just that we don't really have much of a choice?
What do you expect in a country that charges pennies for gasoline and has roads with no corners? It all contributes to the creation of inefficient line-runners. Your cars are typified by their ability to consumer an abundance of resources, just like their owners.
What about because people need the extra room? Or because the hybrid cars are too expensive? Or because they dont go as fast?

Oh and the Prius is doing quite well, and the Leaf is getting much better.
Suicidesoldier#1's avatar

Fanatical Zealot

Well, they don't meet emission standards among other things, too much pollution.

And mpg is over rated, usually, as something like going from 20 mpg to 40 mpg is really only like 11% improved fuel efficiency.


It also depends on speed; energy = 1/2(mass)(velocity) squared.

So if you go 60 mph you will be using 4 times as much energy as 30 mph, and 9 times as much as 20 mph.


So the slower you go the better gas mileage you get; so the mpg is pretty much worthless.

You should gauging it by efficiency, which is supposedly 20% mechanical efficiency for your average car.


But even then it's off; you end up getting like, 8 mejajoules worth of energy for every gallon of gasoline with has like 40, but the thing is, over 66% of the weight of the exhaust is oxygen!

You end up getting a lot of the energy from the air; now whether this is calculated in or not depends on a lot of things. So the average car really only gets like 6% chemical/thermal efficiency for the gasoline. By that measure cars at 100% efficiency would be 15 times better not 5 and their efficiency could be much higher.


So where do we even begin to start measuring calculations?

It's just impossible to do; what we should do is burn gasoline in giant steam turbines EASILY tripling to quadrupling it's energy supply and then of course only being reliant on local sources (in 2004 our peak oil supply from foreign countries was like 65% and supposedly it's going down, so we could supply our own oil just from ourselves if we were 3 times more efficient) whilst switching over to electric and eating up most our carbon dioxide with algae (and then turning that into 10% more ethanol which is basically 10% free fuel which for the fuel efficiency would be like 30-40% improvement easy), but that's too easy.
Suicidesoldier#1
Well, they don't meet emission standards among other things, too much pollution.

And mpg is over rated, usually, as something like going from 20 mpg to 40 mpg is really only like 11% improved fuel efficiency.

"Only" 11% improved fuel efficiency? Well, we may as well just give up, then.
Quote:
It also depends on speed; energy = 1/2(mass)(velocity) squared.

So if you go 60 mph you will be using 4 times as much energy as 30 mph, and 9 times as much as 20 mph.


So the slower you go the better gas mileage you get; so the mpg is pretty much worthless.

Yeah, except they don't test the fuel efficiency at 0mph, and there's a lot more factors in effect than simply the speed of the car, like the transmission and the car's momentum.

Quote:
It's just impossible to do; what we should do is burn gasoline in giant steam turbines EASILY tripling to quadrupling it's energy supply and then of course only being reliant on local sources (in 2004 our peak oil supply from foreign countries was like 65% and supposedly it's going down, so we could supply our own oil just from ourselves if we were 3 times more efficient) whilst switching over to electric and eating up most our carbon dioxide with algae (and then turning that into 10% more ethanol which is basically 10% free fuel which for the fuel efficiency would be like 30-40% improvement easy), but that's too easy.
Ethanol is a terrible fuel and the time for burning gasoline has long past.
Suicidesoldier#1
But even then it's off; you end up getting like, 8 mejajoules worth of energy for every gallon of gasoline with has like 40, but the thing is, over 66% of the weight of the exhaust is oxygen!

Source please. How can there be more oxygen in the exhaust than in the air if the car depends on the combustion of oxygen?
Suicidesoldier#1

It also depends on speed; energy = 1/2(mass)(velocity) squared.

So if you go 60 mph you will be using 4 times as much energy as 30 mph, and 9 times as much as 20 mph.


So the slower you go the better gas mileage you get; so the mpg is pretty much worthless.


The final conclusion is correct but your reasoning is wrong.

1/2mv^2 is kinetic energy; once you're moving you have that energy and that's it.
If you go from 0 to v, you need 1/2mv^2 + losses and that's it, you don't need more energy.

To maintain that speed you need to overcome the losses slowing you down.
Fuel consumption goes up with speed because losses go up with speed. The most obvious of this is air resistance which is approximately proportional to v^2.
Oil consumption makes people rich, rich people buy congressmen, the president, and votes. Rich people decide what cars you will be offered. Rich people also control the media which defines the image most americans have of themselves. So in almost every way rich people decide what cars we will be allowed to buy so that they can make money off of oil and the cars we buy. People say they want to fight the rich, but they really do not want to fight the rich. You see the rich make their lives better by giving them entertainment and bling. If they lived by what they needed they would have to find joy in the little things and pass up a lot of the luxuries the rich provide in order to shatter their dependence on the status system that keeps the rich in power. It is like leaving a pile of heroin in front of a junkie and then telling them all about how bad it is to use drugs. All you do is waste your breath and have a junkie that will never leave you alone.

No, the only correction that will happen will be the one that comes at the end of the oil.
tererun the horrifying
Oil consumption makes people rich, rich people buy congressmen, the president, and votes. Rich people decide what cars you will be offered. Rich people also control the media which defines the image most americans have of themselves. So in almost every way rich people decide what cars we will be allowed to buy so that they can make money off of oil and the cars we buy. People say they want to fight the rich, but they really do not want to fight the rich. You see the rich make their lives better by giving them entertainment and bling. If they lived by what they needed they would have to find joy in the little things and pass up a lot of the luxuries the rich provide in order to shatter their dependence on the status system that keeps the rich in power. It is like leaving a pile of heroin in front of a junkie and then telling them all about how bad it is to use drugs. All you do is waste your breath and have a junkie that will never leave you alone.

No, the only correction that will happen will be the one that comes at the end of the oil.

Or the end of status.
Eveille's avatar

Sparkling Reveler

I have to agree with tererun. Status and acculturation are more important factors than knowledge in determining what people will buy.

There were several guys in my environmental science classes, graduate level even, who had pick ups for themselves. Just themselves. They said they liked them and they didn't want to trade it in for something more efficient. Just like that.

I also read several sociology papers that state that education helps people make better choices, but that in the end it comes down to 'what will my friends think? what will my neighbors say? do I fit in?...' Stuff like that, how much do these objects fit in with peoples prejudices about life. Then how much it costs and how affordable it is in choosing whether to buy a new thing.
Je Nique vos Merdiers
tererun the horrifying
Oil consumption makes people rich, rich people buy congressmen, the president, and votes. Rich people decide what cars you will be offered. Rich people also control the media which defines the image most americans have of themselves. So in almost every way rich people decide what cars we will be allowed to buy so that they can make money off of oil and the cars we buy. People say they want to fight the rich, but they really do not want to fight the rich. You see the rich make their lives better by giving them entertainment and bling. If they lived by what they needed they would have to find joy in the little things and pass up a lot of the luxuries the rich provide in order to shatter their dependence on the status system that keeps the rich in power. It is like leaving a pile of heroin in front of a junkie and then telling them all about how bad it is to use drugs. All you do is waste your breath and have a junkie that will never leave you alone.

No, the only correction that will happen will be the one that comes at the end of the oil.

Or the end of status.


The end of oil is the only option of those that are remotely possible.
Suicidesoldier#1's avatar

Fanatical Zealot

Gharbad
Suicidesoldier#1

It also depends on speed; energy = 1/2(mass)(velocity) squared.

So if you go 60 mph you will be using 4 times as much energy as 30 mph, and 9 times as much as 20 mph.


So the slower you go the better gas mileage you get; so the mpg is pretty much worthless.


The final conclusion is correct but your reasoning is wrong.

1/2mv^2 is kinetic energy; once you're moving you have that energy and that's it.
If you go from 0 to v, you need 1/2mv^2 + losses and that's it, you don't need more energy.

To maintain that speed you need to overcome the losses slowing you down.
Fuel consumption goes up with speed because losses go up with speed. The most obvious of this is air resistance which is approximately proportional to v^2.


There's a variety of factors present.

Maintaining the speed, air resistance, all sorts of things.


Some cars do actually get better gas mileage at say, 60 than they do at 45 but it has to do with air resistance and the aerodynamic design of the car.

Long story short attempting to assert what the gas mileage of a car is and how to ascertain the single variable responsible for the car is ludicrous to begin with.
Suicidesoldier#1's avatar

Fanatical Zealot

Je Nique vos Merdiers
Suicidesoldier#1
Well, they don't meet emission standards among other things, too much pollution.

And mpg is over rated, usually, as something like going from 20 mpg to 40 mpg is really only like 11% improved fuel efficiency.

"Only" 11% improved fuel efficiency? Well, we may as well just give up, then.
Quote:
It also depends on speed; energy = 1/2(mass)(velocity) squared.

So if you go 60 mph you will be using 4 times as much energy as 30 mph, and 9 times as much as 20 mph.


So the slower you go the better gas mileage you get; so the mpg is pretty much worthless.

Yeah, except they don't test the fuel efficiency at 0mph, and there's a lot more factors in effect than simply the speed of the car, like the transmission and the car's momentum.

Quote:
It's just impossible to do; what we should do is burn gasoline in giant steam turbines EASILY tripling to quadrupling it's energy supply and then of course only being reliant on local sources (in 2004 our peak oil supply from foreign countries was like 65% and supposedly it's going down, so we could supply our own oil just from ourselves if we were 3 times more efficient) whilst switching over to electric and eating up most our carbon dioxide with algae (and then turning that into 10% more ethanol which is basically 10% free fuel which for the fuel efficiency would be like 30-40% improvement easy), but that's too easy.
Ethanol is a terrible fuel and the time for burning gasoline has long past.


Well I mean it would be a good use of it until we switched over to thorium and then eventually solar panels in Antarctica. 3nodding

It's not my primary recommendation but it would do.
Suicidesoldier#1's avatar

Fanatical Zealot

Sarah Louise Kerrigan
Suicidesoldier#1
But even then it's off; you end up getting like, 8 mejajoules worth of energy for every gallon of gasoline with has like 40, but the thing is, over 66% of the weight of the exhaust is oxygen!

Source please. How can there be more oxygen in the exhaust than in the air if the car depends on the combustion of oxygen?


Uh...

O2 is what we breathe.


Then you get C02.

The hydrocarbon reacts forming water and carbon dioxide (and it pollutes cause it's a dirty reaction but...)


So a 6 gallon thing of gas ends up making about 15-18 pounds of exhaust.

Crazy I know.
Suicidesoldier#1
Gharbad
Suicidesoldier#1

It also depends on speed; energy = 1/2(mass)(velocity) squared.

So if you go 60 mph you will be using 4 times as much energy as 30 mph, and 9 times as much as 20 mph.


So the slower you go the better gas mileage you get; so the mpg is pretty much worthless.


The final conclusion is correct but your reasoning is wrong.

1/2mv^2 is kinetic energy; once you're moving you have that energy and that's it.
If you go from 0 to v, you need 1/2mv^2 + losses and that's it, you don't need more energy.

To maintain that speed you need to overcome the losses slowing you down.
Fuel consumption goes up with speed because losses go up with speed. The most obvious of this is air resistance which is approximately proportional to v^2.


There's a variety of factors present.

Maintaining the speed, air resistance, all sorts of things.


Some cars do actually get better gas mileage at say, 60 than they do at 45 but it has to do with air resistance and the aerodynamic design of the car.

Long story short attempting to assert what the gas mileage of a car is and how to ascertain the single variable responsible for the car is ludicrous to begin with.
The method you used to claim that the faster you go the more fuel you use is completely nonsensical.

The basic kinetic energy formula means that's how much energy the car HAS, not how much it is using. The amount of fuel a vehicle uses at ANY speed will be based on the RPMs of the engine in the gear it is in. If I could keep my RPMs less than 4800 by shifting at the correct point, I would have better fuel efficiency than if I went all the way to the redline before I shifted. That's why we have overdrive and higher gears. That's why I get WAY better mileage doing interstate driving at high speed but low RPMs to maintain it than I do thrashing around offroad at low speed with high RPMs to maintain my momentum.
We are slowly increasing the number of gears in a transmission so that we can keep RPMs to a minimum at any speed or power range.

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