Talk-Polywell.org

I hate these "studies" that somehow never actually go out and find out what really happens in the real world:
http://www.greencarcongress.com/2010/04 ... rom-r.html

Ridiculous. Speed limit from Casper down to Laramie is 65. I was going 80, just because I could. Unless you put a ton of cops on the roads, not many people will slow down a whole lot.

Something else I've heard is that they're still designing cars to drive at 55 MPH or so, rather than the higher speeds we normally use. When I first saw what you said, I though this was what they were saying--lower speeds are more efficient. Redesign for the higher speeds would work much better.

This is just a stupid liberal idea. I know a lot of my driving is in town, where this would do little to affect my driving habits. And people who choose to drive long distances don't do it because they want to save time.

Yeah, velocity dependant forces are a liberal conspiracy.

I agree this is not the way to increase effiiciency, but please at least be rational about it.

I am pretty sure that neither Jc nor "kunk" think that physics is a liberal conspiracy. Nor do they think that faster is more efficient. There is a question of whether the study demonstrates that the SOCIAL engineering of reducing the speed LIMIT (vice speed) will have the desired effect.

Cars optimized for 55mph and used at 80mph are less efficient than cars optimized for 65 or 75 and used at 80. Without the intrusive enforcement that most folks don't want, the type of REGULATION proposed due to this type of study will probably be counter-productive. Such is often the case with a "Liberal" agendum. What most liberals never seem to learn is the "oughta" ain't "is". Social "engineering" oughta work. Usually, it don't.

The reason is simple to understand with a viable moral science, but that is another topic!

If you make a car more efficient at 70 is will be that much more efficient at 55. How do you propose bending the power to efficiency curve?

kcdodd wrote:If you make a car more efficient at 70 is will be that much more efficient at 55.

True, but folks are GOING to go 65 to 75, or even 80 miles per hour. If you want to save rock-oil do you want them in a car that is optimized for 70 mph or one that is optimized for 50 mph?

I don't think you quite get what I am saying. So let me try to describe it with physics.

The force slowing down the car to first order goes as F=f*v, which depends on velocity. Power output is P=F*v. The rate of fuel consumption has a base rate to keep the engine going plus a power conversion efficiency, r=b+c*P. Fuel economy is velocity divided by consumption rate; Q=v/r. So you have:

Q=v/(b+c*f*v^2)

Taking the derivative to find the optimum:

V_opt = sqrt(b/(f*c))

And

Q_opt = 1/(2*sqrt(b*c*f))

So, to increase the optimum velocity you either have to increase base consumption, decrease conversion consumption, or decrease drag. Only two are preferable (decrease drag and increase eff). Doing either one will increase all effiiciencies, not just the peak. So, car companies are not just stupidly making you drive slow.

kcdodd wrote:I don't think you quite get what I am saying. So let me try to describe it with physics.

The force slowing down the car to first order goes as F=f*v, which depends on velocity. Power output is P=F*v. The rate of fuel consumption has a base rate to keep the engine going plus a power conversion efficiency, r=b+c*P. Fuel economy is velocity divided by consumption rate; Q=v/r. So you have:

Q=v/(b+c*f*v^2)

Taking the derivative to find the optimum:

V_opt = sqrt(b/(f*c))

And

Q_opt = 1/(2*sqrt(b*c*f))

So, to increase the optimum velocity you either have to increase base consumption, decrease conversion consumption, or decrease drag. Only two are preferable (decrease drag and increase eff). Doing either one will increase all effiiciencies, not just the peak. So, car companies are not just stupidly making you drive slow.

This is except that cars are driven by engines. an engine has an optimum design point, where the ignition is set, the timing is matched and the engine is in full tune. This is different for different cars and can lead to some interesting results when you see, for instance a Ferrari driving at regular highway speeds. My main point though wasn't about car efficiencies, but time efficiencies. By arbitrarily lowering the speed limit you create time inefficiencies as things take longer, traffic builds up and people waste time switching to other modes of transport. Studies like this never take wasted time in to consideration. Yet time is the one thing you can never make back. I think that's it;s just as wrong for a gov't to steal time as it is to steal money. Progressives always feel the need to do both.

It does not make them idiots for having different priorities than you. Nothing you said refutes the conclusion of the study, which is that driving slower would reduce emissions.

kcdodd wrote:Yeah, velocity dependant forces are a liberal conspiracy.

I agree this is not the way to increase effiiciency, but please at least be rational about it.

The liberal conspiracy is that time is of no value to humans.

If time is of no value I think 30 mph is optimum for fuel economy. Liberals do not have the courage of their convictions.

kcdodd wrote:It does not make them idiots for having different priorities than you. Nothing you said refutes the conclusion of the study, which is that driving slower would reduce emissions.

What makes them idiots is trying to impose their values on people with different priorities. But it doesn't work. Highway speed on the Interstates is 80 mph. The laws are ignored. So the law is not really a way to improve efficiency. It is a way to enhance revenue. i.e. government sanctioned highwaymen.