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.
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
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
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
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.
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.
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.
replace "roosters" with "cox" to reply.
Yes it does. The vast majority of the energy in a tank of gasoline is simply
as 'waste heat'. About 3/4 is wasted in fact.
An ICE is also less efficient at cruise than it could theoretically be because
drag from the throttle when it's not fully open. It creates air drag for the
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.