# Is the Hummer "greener" than the Prius?

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• posted on June 18, 2007, 3:51 am

Depends on what your wife meant by "small car". Either way, I think I would take my chances with the Hummer.

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• posted on June 19, 2007, 4:01 am

How fast was the small car going? A Mini Cooper doing 100mph can do a lot of damage, equal to or greater than a full sized car doing only 20. E=MCsquared.

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• posted on June 19, 2007, 11:55 am
Mike Dobony wrote:

E = MC^2 (E = Energy, M = mass of the object converted to energy, C the speed of light in a vacuum, ^ 2 means squared) means that matter can be converted to energy and vice versa. This equation is only relevant here if either the Mini Cooper is blows up in an atomic explosion. Last I check, Mini Coopers are not made of uranium.
The relevant equation is E = 0.5 MV^2, where the kinetic energy E = the mass of the object M, and V = the velocity of the object.
http://en.wikipedia.org/wiki/Kinetic_energy
Jeff

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• posted on June 19, 2007, 12:53 pm

Gee, yer smrt.

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• posted on June 4, 2007, 3:44 pm

As long as we're penciling in aspects that the EPA failed to quantize, lets look again at my favorite failing of conventional IC engine driven vehicles, and that is the necessity for the engine to idle during the 0 to 5 mph crawl on a clogged freeway. We all know that the slower a Prius moves, the more efficient its use of energy becomes. In fact when it stops, the engine turns off, and will stay off if there are no other energy demands for lights or cabin heat. The electric drive system meters out only what energy is necessary to overcome tire rolling resistance and inch the vehicle along in the slow-moving line. No heat - - no fumes - - not even carbon dioxide - - until the battery needs to be topped off for another 2 or 3 miles of emission-free driving.
It's interesting, I was in Palo Alto, Friday, for the big Keeble & Shuchat camera bash (they paid the sales tax - - however - - only after charging quite a bit more than on-line pricing for their products). Back to the subject - - I never saw so many Prius automobiles in one place. I'd say every 5th, or so, car was a Prius. Palo Alto, of course, is a community of the rich, and they know how to save money on gas, and probably like to breathe. The less well-to-do have to drive their smogmobiles until their MPG figures become unbearably low, and even then in their ignorance, they go and buy another smogmobile. Okay, so much for the biased viewpoint of a Prius owner. YES!!!!!!

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• posted on June 4, 2007, 6:14 pm
Chuck Olson wrote:

Whilst you're right about that point, the truth is far, far worse.
In order to obtain acceptably 'brisk' acceleration from a car, it's quite normal to have an engine of say 100 bhp even in a small car, yet to propel it at say 80 mph on a flat road would only require ~ 20 bhp (to overcome air ressitance and rolling ressitance from the tyres). And yes. I've worked those figures through.
That 100 bhp engine is horribly inefficient at 20 bhp of output. It's still creating vast amounts of waste energy that the cooling system has to remove for example.
In the case of a 200, 300 or 400 bhp engine the waste is worse still.
The great thing about electric motors is that they work at high efficiency over a huge range of power outputs, so you can happily have even a 200 kW ( ~ = bhp) electric motor for blistering acceleration and it *will* be efficient in the cruise too. No waste heat to talk of you see.
Graham

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• posted on June 5, 2007, 12:55 am

This is a fundamental misunderstanding of how engines work. An ICE does not create vast amounts of "waste energy" in some manner proportional to the difference between its power output and its maximum power capacity.
--
There's no such thing as a free lunch, but certain accounting practices can
result in a fully-depreciated one.

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• posted on June 5, 2007, 1:02 am
Matthew T. Russotto wrote:

Well, you're both kind of right. An ICE is *always* creating waste energy when running, and its efficiency does depend on power output, and it tends to be more efficient in terms of BSFC when heavily loaded.
nate
--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

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• posted on June 5, 2007, 1:51 am
Nate Nagel wrote:

All of which scores horribly against an electric motor which has none of these drawbacks and boasts > 90% efficiency too.
Graham

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• posted on June 5, 2007, 2:10 am

Until you realize that the electricity has to get to the electric motor somehow. Generation efficiency, transmission and distribution losses, and conversion losses all take their toll then.
--
There's no such thing as a free lunch, but certain accounting practices can
result in a fully-depreciated one.

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• posted on June 5, 2007, 2:20 am
"Matthew T. Russotto" wrote:

None of the above have to happen on the vehicle itself.
That's the unique strength of electric propulsion.
Graham

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• posted on June 5, 2007, 1:43 am
"Matthew T. Russotto" wrote:

Yes it does. The vast majority of the energy in a tank of gasoline is simply wasted as 'waste heat'. About 3/4 is wasted in fact.
An ICE is also less efficient at cruise than it could theoretically be because of the drag from the throttle when it's not fully open. It creates air drag for the engine..
Graham

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• posted on June 5, 2007, 2:05 am

Both are true, but they don't contradict my statement.
--
There's no such thing as a free lunch, but certain accounting practices can
result in a fully-depreciated one.

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• posted on June 4, 2007, 5:56 pm
"R.Hemmu" wrote:

Utter bollocks.
Americans really know how to lie big time. And all to keep their retarded SUVs.
Graham

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• posted on June 5, 2007, 12:40 am
Eeyore wrote:

We don't need to lie to keep our SUVs (and I wouldn't ever own one myself). We have this thing called freedom.

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• posted on June 5, 2007, 1:36 am
"Fred G. Mackey" wrote:

Freedom to be an AMERICAN IDIOT !
God bless you for your arrant stupidity.
Graham

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• posted on June 5, 2007, 2:33 am
Eeyore wrote:

Or to not be one. The freedom to be idiotic or not does not seem to exist where you come from - either that or most of you have chosen to be idiots.

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• posted on June 4, 2007, 6:14 pm
cost vs co2 output are not the same...

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• posted on June 4, 2007, 6:22 pm
GO Mavs wrote:

You assume CO2 output is even the real issue.
Graham

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• posted on June 4, 2007, 6:42 pm

If you are speaking of "greener" then it is. Unless you mean greener as in money wise. Even then, if you were to replace the battery at 4 thousand dollars.. the cost is still better.