My random thoughts after 1 week of ownership

Welcome to the club! Sounds like you're well on your way to a long, happy relationship. And the fiance is a good start, too!
I don't like "Pryus" either---too close to priapism. Though some might argue the higher mpg makes some guys VERY excited?
For your lifetime mpg, keep a manual log of fillups and miles... I believe the MFD display will reset the MPG value when you fill up with a significant-enough number of gallons.
I'm astonished when people spew out so much misinformation, and then blatantly refuse to hear the other side, let alone debate the two sides!
Happy Miles!

 

I thought there was a way to see the lifetime MPG, but I guess not. I couldn't find it on the 07 Prius I rented and I dont have mine yet. It's surprising they wouldn't make a setting that shows lifetime MPG. Too bad.

It's definitely pronounced Pree-us. The adjective "prius" is pronounced pry-us, but not the car.

Welcome to the 28 year olds Prius owners cliub! On another thread talking about demographics I found out a huge percentage of Prius owners are exactly 28. Weird!

Anyway, on Monday I'm picking up mine from the Bay Area too. Seems you have there the biggest selection of Piuses. Magnetic Grey was the color I initially wanted, but since I could never see what it looked like in person, I went for the Seaside Pearl, because I saw it and I liked it.

Enjoy!

 

You can go to this link and buy an Engine Block Heater from the PriusChat Group Buy. Copy and paste it.
http://priuschat.com/Engine-Block-Heater-E...-19-t36498.html

This will take you from your 20-25 MPG first five minute bar to near 40 MPG. In the summer you only need to heat about 3 hours to achieve this (if you purchase a timer). On average this 400 Watt heater at a daily cost of about $0.10/day is quite efficient. You will see the best results with the EBH in the winter time. You will need to adjust your times accordingly when it gets cold. Just PM Danny on the link provided to get one at the group rate. Good luck with maximizing your MPG's.
D Rock

 

Glad you're enjoying it. It sounds like you're really getting the most out of it and that you will soon be starting to convert others

Just one thing I wanted to point out about what you said:

<div class='quotetop'>QUOTE(AXavier @ Jul 26 2007, 08:44 PM) [snapback]485872[/snapback]</div>

This is a common misconception with the Prius: that you should try to use the battery. There are all sorts of losses that come in when you use electric (i.e. charging the battery, discharging the battery, friction in the generators, etc.) It's important to remember that ALL the power that the Prius uses to go ultimately comes from the ICE (i.e. gasoline-powered). So, instead of trying to use the battery, a more effective strategy is to focus on how to most efficiently use the ICE. Sometimes this will involve using the battery, but one of the most effective fuel-saving strategies is the so-called "pulse and glide," which involve brisk acceleration up to a speed (i.e. using the ICE at moderately high RPMs), and then "gliding" down to a somewhat lower speed. Note that, in a perfect world, the electric motor never comes into play.

One of the reasons that the Prius has an electric motor is because it uses an Atkinson (?) cycle ICE, which is efficient at medium to high speeds, but has lowish torque at low speeds. This is where the electric motor comes in: it provides the low-speed torque.

 

Life is good :_>

 

<div class='quotetop'>QUOTE(AXavier @ Jul 26 2007, 08:15 PM) [snapback]485913[/snapback]</div>

It's worth pointing out that you get nothing for free. If you drain the battery, eventually the engine will have to run to recharge it. So it's not true (as you said earlier) that the demonstrations in the parking lot don't use any gas; they just don't use any gas THEN. It's like borrowing money from the bank: you have to pay it back eventually!

On the other hand, if (by dint of going downhill, for example) you get a bunch of green bars, the battery use sure FEELS free, doesn't it? Still, you have to go back uphill eventually, so you pay for it then.

And as someone pointed out, getting energy into and out of the battery incurs losses that using the engine wouldn't incur. So it really is better to drive normally and let the car do its thing.

Not to burst your bubble: it's still the absolute best car I've ever owned, and it's really a kick to get 45+ MPG on a commute that my Jeep Grand Cherokee use to get about 15 MPG at best on. I laugh all the way past the gas station!

Welcome to the club: if I see you waving, I'll wave back!

 

<div class='quotetop'>QUOTE(Betelgeuse @ Jul 26 2007, 10:57 PM) [snapback]485906[/snapback]</div>

With apologies because this isn't specifically intended to reply to the above so much as comment on the generalities of these sort of statements - but in broad terms I simply don't see how this can be. If the motive power of the Prius was as simple to represent as this, why bother with an electric engine and battery in the first place. Why not save all the weight and complexity of the battery, motor/generators etc, and get better fuel efficiency by leaving them out altogether.

Take as an example a part of my daily commute. It's around two miles of level and then undulating/gentle down-slope with a 35mph limit and an intersection with traffic light at the end. Arriving at the start of this I can get into EV mode easily, and remain there for the whole section. As I approach the end, the limit drops to 30 and as I slow for that and the lights, regenerative braking feeds sufficient energy back to the battery that it is back at the same state of charge as when the section started (in fact sometimes higher). No energy for this comes from the engine, except the original state of charge which is replenished, so there is no net loss.

If I drive that section 'normally' in the Prius, instead of the 99.9 segment on the MFD I get one that shows close to 50.

Then, to counter the 'if you gain going downhill you loose going up' comments, returning that way with the engine already warm, the up slope is sufficiently gentle that if I want, I can do most of that in EV too, though the undulating sections allow some recharge of the battery also, such that the state of charge is generally no worse than one bar less than it was at the start. Driving that 'normally' renders a segment showing about 40mpg instead of the 70 using EV.

I'm no scientist, but it seems plain to me that at least to some degree, energy from the battery being used to power the car via the motor and then reclaimed in regenerative braking is assisting in obtaining improved mpg over the combustion engine alone. It also seems to me that inherently, electric motors are more efficient in converting energy to movement than an internal combustion engine can be, so the relatively small losses in discharging and recharging the battery (causing heat) are an improvement over the relatively large efficiency losses inherent in using internal combustion engine for the same thing.

 

<div class='quotetop'>QUOTE(ZA_Andy @ Jul 27 2007, 04:36 AM) [snapback]486017[/snapback]</div>

To repeat: it is physically impossible to get energy for "free." At some point, you are running the engine extra hard to recharge that battery. If you go up a hill and lose charge, then go back down, you'll regain SOME of the charge, but not all (due to losses). No way will you be able to come down that hill and end up with the battery MORE charged than when you go up, without burning SOME gas to do it.

All this is a consequence of the two laws of thermodynamics: 1. you can't win (you can't get energy for free). 2. you can't break even (that is, any energy transfer involves losses).

Oh, and I AM a scientist with a Ph.D. in physics. So I presumably know what I'm talking about.

The reason for the battery and electric motor generators is to reclaim SOME of the energy that would otherwise end up as heat in the brake pads and drums. So the battery DOES help, it just doesn't give you free energy.

 

<div class='quotetop'>QUOTE(kimgh @ Jul 27 2007, 10:07 AM) [snapback]486072[/snapback]</div>

Excuse me for rattling your cage, but I didn't say I was getting energy for free, just making a practical observation from a real world use of the car, including the difference in fuel economy noted using two different driving techniques on the same stretch of road. Interestingly, since my mpg goes up when I drive using the former technique when compared to the latter, I quite obviously wrongly conclude that inclusion of the battery and all that hybrid gubbins actually helps. Silly me.

I'll shut up and leave it to you 'experts'.

 

<div class='quotetop'>QUOTE(AXavier @ Jul 26 2007, 11:15 PM) [snapback]485913[/snapback]</div>

None of the above. Flooring it wastes gas, accelerating on the battery wastes gas.

There seems to be pretty good agreement among the knowledgeable posters that you get best engine efficiency with "brisk acceleration", defined as accelerating with RPM between 1900 and 2300 by some, defined as pedal position at 38% of maximum by others (call it bit over a third of the way down, say). You'd need an aftermarket plug-in (e.g. Scanguage) to read the RPM, but a good rule of thumb posted here is that instantaneous MPG during acceleration should be between 0.5x and 1x your speed in miles per hour, for best efficiency.

I find that I tend to accelerate too slowly unless I pay attention to RPM. (I bought a scanguage to display RPM).

Why? Why is this true.

Point 1 is that the ICE is most efficient at a mid-range load. If you're loafing along or pushing it very hard, the efficiency drops.

Point 2 is that the energy for the battery comes from the ICE, and the round-trip into and out of the battery (charge the battery up, use it to propel the car) wastes (at least?) 20% of the energy.

So the rule of thumb is: if you can use the ICE at moderate load, do so. Propel the car on electricity alone only during what would otherwise be unavoidable low-load situations for the ICE.

So a typical city cycle is: accelerate relatively briskly to speed, then feather the pedal to shut off the ICE and glide on electric at 35 mph. Brake as slowly as traffic allows to allow for best energy recapture during braking, but in fact the data suggests that the regenerative brakes capture relatively little of the available kinetic energy of the car due to various limitations, such as the rate at which the battery can absorb electrical energy.

The bottom line is that, in effect, you are trying to use your engine as if it had an on-off switch, to the extent that's possible. If you can, you want to turn it on and run it around (say) 2000 RPM and 55% load. Otherwise, you'd like to shut it off. You don't want to run all-electric in a situation when you could have been running the ICE at an efficient load, because ultimately that's at least 20% less efficient than running the ICE.

So, if you can run the engine at efficient load, turn it on. Otherwise, turn it off. To the extent that's feasible, given speed and traffic.

There are exceptions of course. If you are about to go down a very long hill, you might want to try to drain down the battery to allow for more regenerative capacity. But the point is that they are exceptions.

 

On the pronunciation, since Prius is a Latin word ("goes before"), the "i" would be pronounced with an "eee" sound, so the commonly heard "Preee-us" is correct. It's also interesting to note that the plural of Prius in Latin is Priora.

 

I remember seeing a year or two ago somewhere buried in this site someone's system efficiency testing and analysis results including the wheel-to-gen-to-battery-to-motor-to-wheel efficiency as 30%.

 

[snip]
chogan explained that well enough, no need to add to the confusion
[/snip]

Hopefully Someone will start mass production of good EVs soon so then we won't have to argue about whether it's more efficient to use gasoline!

AXavier, welcome to PriusChat! Regarding lifetime MPG, I write down my odometer on my receipt at every fill up, since the receipts have all the other vital info (date, number of gallons, price) and then when I have a couple gas receipts in hand I put the numbers into an excel sheet I made. If you want a copy, PM me, or you can find ones that other people have made and posted online.

 

<div class='quotetop'>QUOTE(kimgh @ Jul 26 2007, 08:38 PM) [snapback]485935[/snapback]</div>

Ahh yes, Grasshopper. All of these things are true, and yet, you have not seen the heart of the matter. It is fun and fulfilling to watch the amazement of the unenlightened when you turn off the A/C and radio, roll down the windows, and roll like the silent ninja through the parking lot.

 

<div class='quotetop'>QUOTE(kidtwist @ Jul 27 2007, 07:52 AM) [snapback]486099[/snapback]</div>

There are plurals of verbs in Latin? :huh:

 

<div class='quotetop'>QUOTE(ZA_Andy @ Jul 27 2007, 10:28 AM) [snapback]486084[/snapback]</div>

Yes, it does. Otherwise, there would be no Prius driver using Prius specific driving techniques getting excellent (i.e., much better than virtually every vehicle on the road) gas mileage. Driving the car like it is a normal car simply will not give you the most efficient use of energy. I'm not driving mine like a normal car and I am currently getting 59+ MPG. Hypermilers do even better.

It is also well known that the efficiency of ICE driven vehicles is much less than the efficiency of electrically driven vehicles. ICEs give you something like 10% of the input energy at the wheels. If you direct drive the wheels on an electric car, you will get a substantially higher efficiency than that. One could make a scientific investigation of the efficiency of use of energy between various means of powering a transportation vehicle. It would be no surprise to me that such a study would conclude that an electrically driven vehicle is much more efficient than one driven by some combustible fuel both in terms of the amount of energy it takes to power the vehicle and how efficiently it is used and in terms of energy source, too. Gasoline takes a lot of energy to produce and is an inefficient medium for the storage of energy. Why do we use it then? Because at the time it became in vogue, it was substantially cheaper than using electricity. Little did they know then of the problems gasoline would cause.

It is all about efficiently using the energy that you have to start with, and, based on real-world experience by real-world Prii drivers, there are means of driving Prii that are more efficient than others.

 

<div class='quotetop'>QUOTE(kimgh @ Jul 26 2007, 11:38 PM) [snapback]485935[/snapback]</div>

Yes, this is quite an interesting phenomenon.

When I first got my Prius last year, I loved the novelty of running on electric and the natural assumption is that this is "better" for overall FE, so I would accelerate normally up to speed, then release and gently press the accelerator to run on electric only, which of course shows awesome instant FE. When I played with Pulse & Glide techniques (admittedly, not that well), I got somewhat better numbers, but never kept it up long enough to make a serious impact on the tank of gas.

However, after a few months when I was less addicted to staring at the consumption screen and reading the posts about how using the ICE is the way to best fuel economy (which seems very bizarre to the un-enlightened), I decided I would leave the display on the Nav map and just drive "normally" as I would any other car, and actually noticed an overall improvement :blink: over my (non P&G) passive driving for EV. :huh:

Just goes to show that generally it is best to just drive with a steady foot and let the car do it's thing... "Just Drive It", as John would say.

 

<div class='quotetop'>QUOTE(Sarge @ Jul 27 2007, 02:01 PM) [snapback]486217[/snapback]</div>

While that may be your experience, it does not match mine. Recently, I have added more "gliding" to my drive, and I find that that has added something like 5 MPG to my overall mileage.

My wife used to drive the car like it was a normal car, and I dreaded that because my mileage dropped substantially each time she drove it.

So, your experience and my experience do not match.


I should probably what I mean by more "gliding." I mean getting the car to the state where there is no visible energy transfer in any direction. No green arrows, no yellow arrow, no orange arrows. No arrows anywhere.