On Sun, 18 Feb 2007 14:23:29 -0700, "Michael Pardee"
This is going to be my last on this subject. I'm not going to
convince you and you're not going to convince me.
You don't point to any hard info on increased efficiency, you just say
it is so. I have read where some of the Toyota and Honda hybrid
customers are not happy. They are not getting the mileage the sicker
says they should. They aren't missing the figure by 4 or 5%, they're
missing it by 25 to 30%. They have gotten some lawyer to file a class
action suit. No great challenge that and filing a law suit doesn't
prove anything, I grant you. But it does show that not everyone is
tickled pink with their hybrid.
I own a 2006 Corolla. It has a small IC engine and gets good mileage
while delivering reasonable performance, that's why I bought it. An
honest 35 to 37 mpg on the highway at 60 mph. Mileage around town is
less but still in the mid 20's. The reason why it gets better mileage
than my Mercury Grand Marquis is because it's small and light and
doesn't have as much engine. Two of the Toyota engines still wouldn't
make the V8 that is in my Merc.
The Merc gets around 28 to 29 mpg at 60 mph but only about 15 to 17
mpg around town. The Merc has 2 major things working against it on
mileage, weight and air resistance. It's about as stream-lined as a
book case and weighs almost as much as 2 Corolla's.
What I'm trying to point out is that I could never get the Mercury to
get the same mileage as the Corolla. If I put the engine and drive
train from my Corolla into my Mercury, it wouldn't get anywhere near
the mileage of the Corolla. But the performance would be a lot worse
than either of them furnish now. Adding an electric motor, batteries
and the control circuitry of a hybrid to the existing drive train of
the Mercury would only further decrease the mileage.
I also will never get the Corolla to be as comfortable as the Mercury.
I can drive the Grand Marquis for hours without getting tired but the
Corolla has me squirming around in less than an hour.
You mentioned that you decided while you were still in high school
that automobiles were inefficient and I agree. But adding more
inefficient elements to the mix won't make for greater efficiency.
I could be a smart a-- here and say that some folks believe in Global
Warming, that CFC's cause the Ozone hole over the South Pole, the
Easter bunny and Santa Claus....but I won't. hehehe
I think I'll go mix some aged ethanol from Tennessee with water and
ice now. I've enjoyed the discussion but I'm not going to respond to
anything else on the subject.
Isn't it amazing what some people do? They buy a car with no intention on
keeping it. Grab the tax incentive, maybe drive a few thousand miles,
complain it doesn't perform like it should and then resell it for more than
The Feds and the IRS just let it happen. What a sham.
As an owner of two Prius, I am very happy. The two cars together have
roughly the same fuel consumption of the 300ZX I traded in, and they are a
joy to drive (I love maneuverability). Most of all, they are the most
reliable cars I've ever had, by a wide margin. To each their own.
BTW... I'm with you on global warming and CFCs, but you're right - let's not
get that started. Have you seen NASA's findings on polar ozone depletion at
http://tinyurl.com/2lkn42 ? Especially interesting is Table 1 on page 59 of
the .doc version.
Don't get the Easter Bunny mad at us, though. I need the chocolate eggs.
How is improving fuel efficiency a political problem?
Your theoretical argument about efficiencies reminds me of
creationists who want to make statistical arguments to claim evolution
couldn't happen. Dude, the proof is right before your face. Hybrids
get much better mileage than a similar/identical car with similar
performance with only an ICE.
I think you misunderstand the statement. If the meaning was "the car reuses
only part of the energy that was regenerated" that matches my experience and
even the logic - there is considerable loss and waste in the process. Toyota
says "up to 30%" of regenerated energy is reusable, so the process is pretty
lossy. But it isn't nearly as inefficient as getting the energy out of an
engine running at 10% power, so it still contributes to the overall gain.
There is a widespread misconception that regeneration is a major source of
the hybrid's efficiency advantage. In actuality, it is a very minor
What are the major contributors, then?
I'd have to assume shutting down the engine at stoplights helps a lot
for the EPA city mileage number.
Good aerodynamics and tires with low rolling resistance, certainly.
Thinking about it, regeneration might be minor, but not "very" minor.
What else could cause the jump from 30 to 50 MPG?
You know, these are topics that have been well talked through in
the not-so-distant past. Google would be your friend.
But: petrol engine's efficiency (Atkinson Cycle IIRC: less power
developed for same displacement as commonplace Otto Cycle engine
yet much better use of fuel) and general engineering qualities.
The notorious electrical bits allow some of the others. A Prius
doesn't break down easily into "this only does that". Parts are
idiosyncratic for more than one reason, often as not.
Day-to-day: engine properly warmed; tyres at right pressure; how
it is driven and maintained; type of fuel.
Reducing the amount of time the engine runs at very low efficiency is the
big one. As the topic illustrates, the present Toyota system isn't very
aggresive at that but it still shuts the engine down and uses electrics
enough of the time to avoid wasting about half the gasoline in low speed
With more powerful electrics (and especially if it becomes practical to
include battery power that will carry a car at full load over major mountain
ranges) the engine can also be downsized. Accelerator response and passing
are the rightful domain of electric power, rather than increasing engine
power and thus reducing efficiency even more in normal use; that darned
Second Law of Thermodynamics again.
It is my belief that you are misrepresenting what I said, taken out of
context. I will try it this way: I generate a certain amount of energy
stored in the batteries, and only use less of that than I would like.
You can view the NHW20 Prius battery charge levels at:
You'd know if you regenerated too much energy by your Prius trying to
get rid of extra charge. People who have just come down a long
downhill (mountain) often report that at a stop their engine will
cycle on/off repeatedly. The Prius will try to bleed off the high SOC
by having one of the electric motors repeatedly start and spin the
(Also, if the hybrid battery cannot accept any more charge, it simply
will not. You will no longer have regenerative braking, and will be
switched to a higher percentage of conventional hydrolic braking.)
If you are just driving around in the green and don't notice anything
else different, then you aren't regenerating more than you can use...
Now that is a website I had not found yet. I will go back to that for a
read, but now right now (bookmarked). Thanks plenty.
My point is just a little bit off from what you are saying (and thanks for
saying it). My angle is that I would like the Prius to use the electric
motor moreso than it does now. I believe that I generate enough that it
ought to do that.
As most have said, the battery has to be charged above a specific threshold
for the ICE to turn off. I have found that you also need to be in cruise
control. Normal driving with foot on the accelerator just doesn't produce
electric-only operation except at very slow side-street speeds. I guess
that's because the Prius computer doesn't trust human beings to drive at a
single fixed speed. My favorite EV speed in cruise control is 34 MPH.
To make sure the battery is charged and ready for EV operation, you need to
apply fairly heavy braking from freeway speed.. Just slowing down slowly
doesn't charge up the battery very efficiently. Unfortunately this kind of
driving is uncomfortable for passengers, so don't do it unless you're alone.
Also, make sure you brake *before* you hit a curve or encounter cross
Doesn't the cruise control need to be reset when the speed drops below a
certain MPH? It does on my Sienna and I believe I read that it does on
the Prius too.
Ah - I found it: "Slowing down to less than 24 MPH (39 km/h) will cause
the cruise-control "resume" memory to reset. So if you have to slow down
or stop, you'll need to set the speed again." - From the Toyota Prius User
So how do you start and accelerate in cruise control in the Prius? What
is the trick?
Also, I have found that normal operation in my Prius keeps the battery
charge near the top of the blue range and often in the green range. There
is no need to perform abnormal braking stunts to ensure adequate battery
Can't answer the "how to start in cruise" part: never tried. If
you think about it, start and/or accelerate are not big parts of
Changing cruise speed I do by the book: flip cruise lever up (+1
mph) or down (-1 mph).
That's just it, I don't think you can. I do see this as a Toyota flaw.
In my Jeep it remembers what the cruise was set at so after paying a toll
you can just go back to the former speed without needing to find it again.
Since that one is a 5-speed, I cannot try to have it go from the startup.
And, yep, changing the cruise speed is just as you note.
I guess every manufacturer does it differently. Honda cruise control
will remember the speed until you shut off the engine or at least the
CC master switch. However, the CC cannot be engaged at speeds below
~20 mph. I think they want to prevent someone from inadvertently
engaging the CC and having the car jump from a stationary position.
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