[Eric]

I've been a lurker on this site for a few weeks, about as long as I have owned a silver 2004 Prius, option package #9 (BC). This is a great site, helpful people, useful information, no ads and not a lot of chatter. Decided it was only fair to share my own impressions of the new Prius.

I've owned many vehicles over the years, from Porsches to Camrys. This is my first Prius, which I came to a little reluctantly, but finally concluded that since I talk green, I'd better behave green.

I'm very glad I made this decision; I couldn't be happier with the vehicle! It is a truly remarkable car. Here follow some comments after 3 weeks and 600 miles:

Fit and finish are superb, I have found no flaws. Only downside is the inevitable "new car paranoia- where can I park this thing and avoid door dings etc.) One minor annoyance is a small rattle somewhere in the center console (maybe the CD changer?) which I can't yet track down. It's only noticeable when things are very quiet, but the Prius is often a very quiet car.

Performance: acceleration is certainly adequate, and I haven't really pushed it yet, followiing the "be gentle" guidelines for its early llife. Handling is nimble, suspension is tight.

Driver visibility: could be better. The low coefficient of drag requires a highly sloped windshield. The front roof posts are also steeply sloped and fairly thick, creating a blind spot. When cornering and in other situations you have to move your head around to make sure there's nothing in the blind spot. Visibility to the rear is also somewhat compromised. Finally, the low hood and rear visibility makes it very hard (for me at least) to know where the edges of the car are. I'm 5'10" so I'm not sitting low, but I can't see the front or the fenders. This makes parking a bit of a guessing game.

So far gas mileage is a little puzzling and not as good as advertised. On a highway trip I got around 53 mpg (mixed freeway and 60 mph highway. Surprisingly my city performance is worse, rather than better as Toyota claims. City average is around 42. I'm not a leadfoot, and in fact have been trying to drive it very gently for maximum mileage. The problem may be that I am driving in near worst case conditions: most of my city driving is short trips, and I live ~400 hundred feet above town, so although I mostly coast down the ICE has to start initially to warm up; that uses fuel. Then returning uphill uses a lot of gas. I notice that when driving around town on the flats mpgs begin to creep up, but when I go back up the hill they get worse. Be nice to see input from others on their gas mileage. At 1000 miles or so I will talk with the dealer and see if they think this is normal. Since I bought the car more for the lack of emissions than the gas mileage if it doesn't get better I won't be devastated, but it's a little disappointing.

Surprise nice feature: the keyless smart entry and start system! I probably wouldn't have gotten this if it hadn't been part of the package, as I am not a big fan of remotes, (especially if they are part of an alarm system. Had a bad experience with a Subaru when locked out with a dead remote and the in-car alarm set. Yes Virginia, you can hot wire a remote). But the Toyota engineers really did a job with this. Being able to walk up to your car with the remote in your pocket, touch the door handle and have the car unlock, get in, press power, and go without ever using a key is a delight. I wish I could get the lock on the door to my house to respond the same way! And if the battery in the remote dies you can still gain access to the car with a key, and start it- truly well thought out.

Enough for now.

 

[Jerry P]

Thanks for the input Eric. This site seems a bit easier to use than the Yahoo ones...and they seem to get a lot of 'chatter' without good info. Your concern about mileage is pretty common right now but I think it will improve in time. My 2001 Echo, which used a variant of the 1NZ-FX engine, didn't really start getting great mileage until I had about 2000 mi. on it, then it was just super - 38 to 42 mpg on a mixed commute. Echo is not really a 'green' car, just LEV, and the PZEV-SULEV rating on the Prius makes it a better choice.

 

[moocatdog]

I've been a lurker on this site for a few weeks, about as long as I have owned a silver 2004 Prius, option package #9 (BC). This is a great site, helpful people, useful information, no ads and not a lot of chatter. Decided it was only fair to share my own impressions of the new Prius.

[snip]

So far gas mileage is a little puzzling and not as good as advertised. On a highway trip I got around 53 mpg (mixed freeway and 60 mph highway. Surprisingly my city performance is worse, rather than better as Toyota claims. City average is around 42. I'm not a leadfoot, and in fact have been trying to drive it very gently for maximum mileage. The problem may be that I am driving in near worst case conditions: most of my city driving is short trips, and I live ~400 hundred feet above town, so although I mostly coast down the ICE has to start initially to warm up; that uses fuel. Then returning uphill uses a lot of gas. I notice that when driving around town on the flats mpgs begin to creep up, but when I go back up the hill they get worse. Be nice to see input from others on their gas mileage. At 1000 miles or so I will talk with the dealer and see if they think this is normal. Since I bought the car more for the lack of emissions than the gas mileage if it doesn't get better I won't be devastated, but it's a little disappointing.

Eric,
As you've been lurking of late, you may know that I'm a new owner too. My driving situation sounds similar to yours and my mpg is about the same as well. I'm getting better (I think) at knowing how to coax the ICE to shut down. One thing that seems to help is to get up to speed fairly quickly and then back off, using the electric motor to maintain speed. My first tank of gas seemd to go quickly; second was better. I'm on my thrid tank now and am averaging 48+. Not what the sticker claimed, but I never really expected to meet those numbers. Low emmisions and high mileage is what sold me on the Prius and I'm perfectly happy so far. When I do get out on longer drives with sustained highway speeds my mileage is jumping way up. The other night, after filling up, I took the freeway downtown and back, with the final couple of miles on surface streets to my home. My mpg for the trip was 73.8! If I have to go back to a regular commute, I could live with that number. ;-)
Moo

[/quote]

 

[patrickg]

I have been reading a lot of talk at this site regarding the desire to "get into stealth mode" as if it were a Holy Grail. I understand where increased mileage for "town driving" comes from and why mileage is lower with sustained high speed driving.

Please someone correct me if I have the following, wrong.

Increased town driving mileage is based primarily on two things: 1. slower driving speeds so less aerodynamic drag and other frictions that are proportional to square of speed and 2. regenerative braking which recycles a fair proportion of energy which would have otherwise gone to heat the brakes.

Lower mileage at sustained high speeds is due to increased aerodynamic drag and other frictions that are proportional to square of speed. If you drive 60 instead of 30, there is 4 times as much drag. Stated another way: if it took 15 HP to drive 30 MPH it would take 60 HP to drive 60 MPH.

OK, now to the quest for the Holy Grail... You can drive such that you maximize the amount of energy you recycle with regenerative braking. You can avoid the need for heavy braking where the friction brakes will rob you of recycleable energy and dissapate it as heat in the brakes. Still, the more you drive on electricity the more, over time, you will deplete the battery and ultimately cause the gas engine to run to charge it back up.

The ultimate source of power for the Prius is the fuel in the tank. There is no such thing as a free lunch. If you manage to maximize the time and distance during which you are using the electric motor, you are postponing not elliminating running the gas engine to charge the battery.

Of course being moderate on the accelerator and the brakes is a good thing for most cars. I think the Prius will give you better mileage if you don't coast as much as with regular cars. With a regular car, coasting up to a stop is a way to use up stored energy of your momentum (overcoming drag and other friction) and have to throw less energy away as heat in the brakes. With regenerative braking, coasting up to a stop light or sign is not the best strategy. Maintaining normal speed closer to the desired stopped position and then using regenerative braking, not heavy braking (which involves friction brakes), as much as possible, maximizes the amount of energy that is recycled.

Perhaps there is a marginal improvement in efficiency to have fewer but longer gas engine "on cycles." That would be one benefit of running in stealth mode as long as possible, sort of gathering up some short gas engine runs into a single, possibly, more efficient long run. I don't see this as much competition for regenerative braking for energy savings.

Maybe some of you automotive genuis types can set me straight.

Pat

 

[moocatdog]

The ultimate source of power for the Prius is the fuel in the tank. There is no such thing as a free lunch. If you manage to maximize the time and distance during which you are using the electric motor, you are postponing not elliminating running the gas engine to charge the battery.

Pat,
I'm not among the automotive geniuses who participate here, but I pursue stealth and warp stealth as much as possible because I think (perhaps erroneously) that the amount of gasoling required for the system to recharge the battery is less than the amount of gasoline required to propel the vehicle at speed. Also because driving in stealth is really cool.
Moo

 

[frenchie]

I pursue stealth and warp stealth as much as possible because I think (perhaps erroneously) that the amount of gasoling required for the system to recharge the battery is less than the amount of gasoline required to propel the vehicle at speed.

This is wrong. Moreover, transforming mechanical energy into electricity and then back into mechanical energy always involves some losses. The only thing to think about in order to maximize fuel economy is to make the engine work in its most efficient zone, and minimize friction on the vehicle (under-inflation of the tyres, friction brakes, air friction because of high speed).

Patrickg, you've got it ! 8)

 

[patrickg]

Sorry, I'll figure out how to delete a message, one day.

 

[patrickg]

the amount of gasoling required for the system to recharge the battery is less than the amount of gasoline required to propel the vehicle at speed. Also because driving in stealth is really cool.
Moo

There is no free lunch. Tough call since efficiencies vary with the engine running at varying RPM but there are losses in each energy conversion. You loose some going from mechanical to electrical. You loose some more storing the electricity. Then you loose some more in getting the energy from the battery to the motor and on to the road. This is likely as or more lossy than connecting the engine to the road. Can't fault the cool aspect. Definitely cool, real cool. I still think an ah-oo-ga horn would be a nice touch.

Pat

 

[efusco]

patrickg,
I think, in the big picture, you're essentially correct. 1)There's no free lunch, 2)fuel efficiency improvement is minimal or marginal at best.

I think the situation is a bit like the EV button issue. Although there are times when the driver can improve the overall efficiency due to his prior knowledge of the route and distance planned.

I've noticed that the ICE will continue to run, as if anticipating my imminent need for it, along runs of 1/2-1 mile in length. Yet, I know that that section is down hill. I can feather into Stealth and actually acclerate slowly along that stretch with enough speed to almost coast up the next little hill with minimal ICE where I then have another longer downhill stretch. I know that there are more downhills for the last 3 miles of my trip home and that I usually end up 'topping off' the battery with the downhills. Thus, I can out-think the ECU in this situation due to my prior knowledge and thus, slightly, increase my efficiency by 'going for' stealth.

At least I think I'm doing some good....
-evan

 

[moocatdog]

patrickg,
I think, in the big picture, you're essentially correct. 1)There's no free lunch, 2)fuel efficiency improvement is minimal or marginal at best.

I think the situation is a bit like the EV button issue. Although there are times when the driver can improve the overall efficiency due to his prior knowledge of the route and distance planned.

I've noticed that the ICE will continue to run, as if anticipating my imminent need for it, along runs of 1/2-1 mile in length. Yet, I know that that section is down hill. I can feather into Stealth and actually acclerate slowly along that stretch with enough speed to almost coast up the next little hill with minimal ICE where I then have another longer downhill stretch. I know that there are more downhills for the last 3 miles of my trip home and that I usually end up 'topping off' the battery with the downhills. Thus, I can out-think the ECU in this situation due to my prior knowledge and thus, slightly, increase my efficiency by 'going for' stealth.

At least I think I'm doing some good....
-evan

Everyone,
As I stated before, I'm not a scientist or an automotive genius, so I'm not surprised to find that my understanding of the stealth's effectiveness may be flawed. However, Evan is describing perfectly the way I've been trying to drive my '04. I've gotten quite good at maximizing mpg (without leaving the battery drained) over the routes that I drive most frequently. I know this because I've checked my mpg and battery charge levels carefully after different trips. In other words, after driving the exact same route under nearly identical conditions I've found that by coaxing the car into stealth mode whenever possible I have increased my mpg without discharging my battery. Is this because I live in a hilly area, so energy is being regenerated as I travel down hills instead of by the ICE? I understand in general terms what you are all saying about energy loss during transfer, but I just thought that if the car has been designed such that driving technique (e.g. using stealth) can increase my mileage, then I should be trying to do that whenever it is practical.
Moo

 

[frenchie]

Moo,

The fact to use stealth as much as possible is not in itself what maximizes MPG, because if you don't use fuel during stealth your consumption is only postponed, not cancelled. But stealth can be indirectly a good way to improve gas mileage if it means you avoid using the engine in its bad efficiency zone. When you're using only electricity, this is because you don't need much power to drive the car; in other words, if you were using the engine at that time it would not be very efficient.

You can have a look at some explanations about Toyota Hybrid System II (or HSD) here :
http://www.toyota.co.jp/IRweb/special_r ... hs2_1.html
and in particular you will find this efficiency diagram :

where the contour lines represent different efficiency levels. Although there is some legend missing, I can tell you the best efficiency is located near the top of the blue curve, approximately at the same vertical position as "Good" and the same horizontal position as "rpm", and the worst efficiency in the low torque region (read this diagram as if you were reading a map with contour lines). The key to a better gas mileage is to make the engine work as much as possible near the "efficiency peak"... or not at all. This suggests a more or less "on/off" driving technique, where stealth mode is used in the "off" intervals... because you can't be accelerating hard all the time !

Besides, the fact that you live in a hilly area is relevant too, and maybe an EV button would in this case, in conjunction with your road knowledge, make MPG even higher, as Evan already pointed out.

Fran�is

 

[moocatdog]

The key to a better gas mileage is to make the engine work as much as possible near the "efficiency peak"... or not at all. This suggests a more or less "on/off" driving technique, where stealth mode is used in the "off" intervals... because you can't be accelerating hard all the time !

Frenchie,
Thanks for the info. I think that's what I've been doing, without understanding the science behind it. After a couple of days of driving the car it seemed to me that I was getting better mpg averages when I got up to speed rather quickly and then, whenever possible, easing off the accelerator and letting the electric motor keep me rolling along. On a related note, isn't it correct that the engine power control unit knows how to run the system most efficiently? If so, wouldn't using cruise control whenever possible be the best method for maximizing mpg? Lately I've been activating it on a rather long hill with a slow 25 mph speed limit near my home and it seems that my mpg is better than when I work the accelerator pedal myself. Am I just imagining things?
I love this car more every day!
Moo

 

[patrickg]

MOO, About the hilly route, hills, in and of themselves, do not represent a serendipitous fuel economy windfall. Irrespective of technique, you will get lower mileage driving through a rolling hill section than an equivalent distance in the flat. Viewing hills as a regenerative "freebie" is not really accurate. Of course your attempts to optimize performance in the hilly section is a good thing.

In a more ideal situation perhaps you'd have superconductor technology in your vehicle and a perfect battery (or other energy storage medium) so you'd recoup the energy used to climb a hill on the way down.

In general, cruise control is an improvement over the driving habits of the "lesser mortals." In many specialized situations, you are probably as good as or better than any production cruise control. You can anticipate and cruise control can't, it can only react after the fact. cruise will throttle back to avoid overspeed on a downslope where you will allow the car to go 5-10 MPH over "set speed" to conserve momentum for the hill you can see is just ahead.

I have driven through some sections of frequent repetitive small but fairly steep rolling hills where my cruise control's response times were such that it essentially got out of phase with needs and did a terrible job.

I am essentially in complete agreement with Francois on the deferred engine run comment. Running the gas engine all the time with no electrical assistance as in a conventional "Infernal Combustion" driven car, mandates the engine to have to operate over a wide range of RPM, even with a CVT trying to level it out. Efficiency can be better optimized over a smaller band of RPM. So you will be less efficient with this arrangeent.

The Prius allows you to espablish an energy account and draw on your reserve when needed and replenish it when you can and need to do so. The replenishment can be done through regeneration and by running the gas engine. The system can run the gas engine to do the replenishment in a more efficient part of its envelope. Thus you use energy as needed but tend to favor high efficiency replenishment.

Oh, by the way, if you drove a "regular" economy car with the care and intensity of purpose you have devoted to driving a Prius, you'd get stellar economy for that model. Most folks just don't do what it takes to optimize economy.

I try to be reasonable with my driving style whether in my 1 ton dually turbo diesel or whatever. A prius represents a retraining challenge as it requires a different driving style to optimize economy. Especially in approaching a stop. With regenerative braking you should maintain speed a little longer into the "stoping zone" and use regenerative braking to recoup your energy of motion. I have practiced for years coasting up to stops to avoid the need for more than light braking. Old dog, new trick, we'll see.

Pat

 

[moocatdog]

Pat,
I think I get what you and Frenchie are saying. My original thought was that the ICE would regenerate elecrical energy more fuel efficiently at parking lot or bumper to bumper speeds because the car would be fighting less friction. However, what you two have shown is that the HSD operates most efficiently at higher RPM, so it is actually more effective to let the HSD control ICE operations (power & regeneration) when working to maintain higher speeds. Hope I'm not boring everyone. <g> And thanks for taking the time to share your knowledge.
Moo

 

[patrickg]

Pat,
I think I get what you and Frenchie are saying. ... so it is actually more effective to let the HSD control ICE operations (power & regeneration) Hope I'm not boring everyone. <g> And thanks for taking the time to share your knowledge.
Moo

Yo! Moo dude, Right on, like. The engineers at Toyota did a decent systems engineering integration. Driving fairly reasonably, to include staying out of the friction brakes, accelerating moderately, keeping the tire pressure up, and possibly running good synthetic lubricants (post breakin) is really about all you need to do to get real good mileage with this well thought out machine. The increased benefits (reduced mileage) that may be had by truly eXtreme driving practices are marginal. You would be way out in the zone of diminished returns. I think this is yet another of those cases where, as is true in many applications, the first 10% of effort gives the first 90% of benefit. All the rest of the effort, at best, can get you the remaining 10%. (benefit here is not defined as raw mileage figures but the increase above average or EPA estimates)

Still, if it brings personal satisfaction to have "bragging rights" to documented MPG averages ahead of the pack, and doesn't lead to unwanted psychiatric scrutiny, then go for it.

Wanna try an experiment? Should we debate the number of angels dancing on the head of a pin when we could use a microscope and count them? Check your mileage for a whole tank (500 miles or so) driving with total disregard for economy. Not purposely driving for poor economy just sort of average Joe driving. Note your MPG for that tank. Then do your absolute best at driving for economy, go total anal, risk psychiatric scrutiny and see what your MPG is for a tank. Then compare these figures to what you normally get and consider how far into the "total effort" zone you are willling to go on a regular basis and what the improvement in MPG would be above the regular Joe. This will illustrate your diminished return on your increased investment and you will know your actual "reward" for your efforts. Know the truth and it will set you free. If that doesn't work try prunes.

Pat

 

[moocatdog]

Yo! Moo dude, Right on, like.

Ummm... I'm not sure if I'm supposed to be entertained or insulted. I'll go with the former.

Wanna try an experiment? [snip] Check your mileage for a whole tank (500 miles or so) driving with total disregard for economy. Not purposely driving for poor economy just sort of average Joe driving. Note your MPG for that tank. Then do your absolute best at driving for economy, go total anal, risk psychiatric scrutiny and see what your MPG is for a tank. [snip] This will illustrate your diminished return on your increased investment and you will know your actual "reward" for your efforts. Know the truth and it will set you free. If that doesn't work try prunes.

That's what I've done between my first tank and, now, my third, and have increased my average mpg from 38+ to 45+ without reducing my average battery charge. Must be my inefficient use of the stealth modes and cruise control. Doh! Isn't it, like, cool how theory sometimes doesn't, like, work in practice?
Moo

 

[patrickg]

"Ummm... I'm not sure if I'm supposed to be entertained or insulted. I'll go with the former."

Good, that was the intention.

There is theory, fact, and belief. Only one of these is for sure all the time. the other two... well, might need adjustment. In a perfect world, theory continuously gets adjusted to track our perception of fact. Belief often hobbles along as best it can.


You may have heard the old one about the bumblebee. Supposedly some aerodynamicists asserted that it was theoretically impossible for a bumble bee to sustain flight, given its weight, wing area, stored energy, and so forth. Of course the bumblebee didn't know all this and flew anyway.

When theory, belief, or perception of fact dissagrees with repeated observation then FACT and or our perception of fact has just changed and hopefully the others will follow.

If you experiment and find what works well for you, it doesn't really matter how that is perceived to allign or not allign with anyone elses preconceived notions or perceptions of fact. Sort of a "if it works good, do it."

My only comment that I thought could have been easily misconstrued to have been negative was regarding diminishing returns. It is a judgement call. How much effort to gain how little improvement constitutes futility. Well, I guess futility is in the eye of the beholder. What drivers in a comercial fleet might do vs what a spirited amature might do as sort of a hobby isn't really germane. If the guys with the butterefly nets don't start chasing you, then you haven't gone too far in your quest for mileage.

I'm not worried until I see drive in Prius temples with a contingency plans of serving "special" Koolaid.

Pat

 

[moocatdog]

I'm not worried until I see drive in Prius temples with a contingency plans of serving "special" Koolaid. Pat

That's when a "stealthy" getaway would come in real handy! Thanks again for taking the time to explain some of the inner-workings of the Prius. I do appreciate it and look forward to learning as much about the car as you and other nice people are willing to share.
Moo

 

[patrickg]

That's when a "stealthy" getaway would come in real handy!
Moo

I have wondered about the quiet approach of a Prius. You really do "sneak up on" folks in parking lots, whether or not intended. I wouldn't be surprised to see some accessory added that makes an auditory alert signal to warn pedestrians that you are coming. Sort of a "going forward in stealth mode" analog to the backup signal on trucks. Of course when hybrids are in the majority, even in company with fuel cell powered vehicles folks will have been retrained to not expect to hear a car and will have to look for them and auditory warnings might become obsolete.

A curious rural fact. Blowing your horn to clear cattle out of your way is a BAD IDEA as most cattlemen train their herds to come to the sound of the horn to be fed. I witnessed a dude and dudette in a sports car impatiently blowing their horn to try to get a single cow out of their way only to attract a couple hundred in quite short order. I have a similar problem with my turbo diesel pickup. A couple neighbors have cattle that are conditioned to come to the sound of a Cumins turbo diesel as they get fed from one. If I drive near them in mine I get mobbed byu cattle who will begin to vent their frustration when no food is forthcoming. Now to tie this to a Prius...

As we will likely be the only rancher folk around here with a Prius, we will probably not get mobbed by hungry cattle. Even if someone did "visit" his herd in a Prius, there might not be too much sound to imprint on. Yet another advantage of stealth mode, sneaking down a driveway that goes through a pasture without attracting unwanted bovine attention.

Pat

 

[leebek]

attractive stealth mode

:lol: Yeah, but you might attract a herd of golfers who think their cart is coming to give them a ride to the next tee...