Prius Shuts Down In Snow

<div class='quotetop'>QUOTE(popoff @ Feb 3 2007, 10:10 PM) [snapback]385057[/snapback]</div>

It doesn't matter how many real-world examples you or any other established forum member can cite. Some Prius apologist will come along and claim that there is no problem and that the Prius performs better than any other car in the snow , and that your problems are due to your flawed driving technique.

Now, here's your cup of purple Kool-Aid, drink up please.

 

"The main point is that there is a software error in 2004 through mid-2005 production that can be corrected wtih a reflash. The ones that just stop dead, that's the likely problem. Properly functioning Prii will "pulse" the drivetrain in that situation (repeatedly spin then stop the wheels), not stop dead.. Go get the car fixed is the answer to that."


Is there a reference as to the cut-in date or vin for cars with the corrected software?

Is there a reference to a Service Bulletin or notice identifying the reflash?

 

<div class='quotetop'>QUOTE(genalex @ Feb 4 2007, 03:11 AM) [snapback]385076[/snapback]</div>

Sorry, I only know this second-hand. My car runs OK in snow, as I described earlier, but it's late 2005. All I know of this is from Tideland Prius' post #19 in the thread that I cited, and the subsequent back-and-forth in later posts. If he Tideland Prius says it, I'm pretty sure it's right, but I have no details.

I'm doing all this second-hand, but I'll throw in my two cents.

First, let me be perfectly clear: if Tideland Prius says it, I believe it. Some cars are fixed by reflash of the known highway stall issue.

Second, it's not clear that anyone acknowledges that the "stopped dead by TRAC" problem in early models was a software issue or that it was fixed by the highway stall reflash. Google variants on "prius trac software fix" and the only relevant thing that shows up is Tideland Prius' post. So I can speculate that Tideland Prius got his TRAC fixed by luck -- it was incident to the stall fix. In other words, Toyota does not admit there is a problem with TRAC in earlier year, and so clearly Toyota does not say that the reflash for the highway stall will fix that TRAC problem.

I have no firm knowledge of that. All I know is what I found when I Googled it.

So -- and here again, this is none of my business, my car runs fine in snow, I'm just bringing up the point -- it's possible that if you bring this up to a dealer, what they'll tell you is either some variant of "there's no TRAC software error" or "you don't need the highway stall fix", but possibly not "we have a well-defined policy regarding the TRAC error and you definitely do not have that problem".

Pure speculation on my part, none of my business, I don't have the problem, I just want to note that , as far as I can tell, there's nothing accessible on the web to show that Toyota admits or is even aware that this is a TRAC software problem in earl models or that the highway stall reflash fixed TRAC for some customers.

All I was doing in the prior thread was reconciling two clearly different classes of posters: those who said "my wheels stopped dead" or variations on that, and those whose cars worked like mine, "the drive train pulses". You can still be dissatisfied with snow performance with that "pulsing drivetrain", I have no problem with that. But if you have the "my car stops dead" issue, well, all I can say is Tideland Prius got his fixed.

I'm rambling. Two failure modes: stops dead versus pulses the wheels. Stops dead may be a software issue, but I don't think Toyota admits it. Pulses the wheels, that's what it does, tough luck. I have no details on the software issue and am not sure Toyota even acknowleges it. All I have one trusted datapoint (Tideland Prius). Finally, with no option to turn off TRAC, I'd say that clearly makes the car less functional on some snow and gravel situations. My solution is that I'm not going to drive mine if there's deep snow, but that's no hardship here, and I've put the instructions for turning off TRAC in my glove compartment, just in case.

 

<div class='quotetop'>QUOTE(priusenvy @ Feb 4 2007, 01:25 AM) [snapback]385065[/snapback]</div>

You're absolutely right. BTW, I like the term "Prius apologist."

I don't particularly like Kool-Aid. Would a glass of OJ work instead?

 

Hi Popoff and Automatic...

If both drive tires slip what is the point of spinning them? The result is that snow underneath the tires will just be pumped out, leave the car hung up on the snow under the car.

The difference you report compared to the other cars could be due to the light weight and larger size of the Prius compared to other cars. The Prius is a pioneer in the use of the high-strength steels, which results in a car that is lighter for its size, and with proper design more resilent in a crash.

My old car, a Saturn SL2 was nearly the same weight as the Prius, but considerablly smaller. Take a run at a snow/slush bank with the SL2, and it would do a good job punching through. It could exert more dynamical pressure on the snow, as it has a narrower design, for the same weight.

Although I have not had the exerpeince in the Prius yet, the aerodynamic smooth and broader underside of the Prius might just high-center, and surf up on top of the snow. This will reduce the force on the wheels and result in less available traction friction. From the outside of the car, a 1/2 inch higher body height, in the snow would not be apparent, but the result could be 500 to 1500 lbs less downforce on the wheels.

My conclusion from your comments, and others on PC about this issue is that this problem is due more to the lightweight design of the Prius, to achieve good fuel economy and crash performance, than a defect in the traction control. Less weght results in easier accelleration in the snow, until one hits snow deep enough to lift the body of the car. This snow level requires the car momentum to push the snow aside. But the Prius being lite-weight and with a surfboard underside, it rides up and looses downforce at the front tires. This hypothesis is consistent with most of the experiential comments, both pro-and anti- Prius traction control.

The engineering response is then, just like the automatic electric A/C with temp control was now a neccessity in the HSD car too keep fuel economy optimised at a level to pay for the HSD, 4WD with electric motors in the rear wheel hubs may also be a neccesity for the high-mileage (lite-weight) HSD vehicle in severe snow conditions. I believe I read someplace that there will be a 4WD option on the next generation Prius.

Another idea would be air-springs, to allow the car to ride higher at the driver's discretion.

The Prius is a pioneer in many respects. Its not that the Prius is the only vehicle moving in these directions however. There are proposed light-weight materials vehicles which would be even lighter than the Prius for its size and load - Amory Lovins Fiberforge project for example. Certainly the GM Fuel Cell skate board concept, now apparently transformed into the Eflex Volt concept is exceptionally lightweight. High mileage needs low-weight. Does anybody have any winter EV1 driving experirences to add to this discussion?

Another aspect of the Prius concept is that the low weight requires low aerodynamic forces to avoid the car being pushed around at highway speeds. Toyota has done a good job of this employing an aerodynamic shape, not a shape based on in-vogue styling ques (at the design time). The aerodynamics also extend to the underside of the car as well, and rather than the snow hooking on underside protrusions which pull the car down, and push snow under the tires, and generate more downforce for the tires in a dynamical situations, the car surfs up on top of the snow. When this happens there is a loss of downforce at the tires, and the tires loose traction. Once the tires spin, the computer turns them off.

 

<div class='quotetop'>QUOTE(automatic1stdown @ Feb 3 2007, 10:39 PM) [snapback]385047[/snapback]</div>

I find TRAC configured to be too sensitive myself. However, on my 07, I don't see the same behavior as you and "Christopher". If other people's 07's are the same as mine, it's not reasonable to say that this problem will exist for new buyers. Maybe mine is a quirk? I've seen people saying it happens and that it doesn't happen, but the story did not reflect that.

Having said that, I'm all in favor of seeing some software changes to TRAC for my car as well.



<div class='quotetop'>QUOTE(chogan @ Feb 4 2007, 04:07 AM) [snapback]385085[/snapback]</div>

Still not sure if anyone has read the Toyota technical blurb pdf I posted, but it seems clear to me that pulsing the wheels on a slippery incline is not a failure mode, but rather how the car is designed to get up a slippery hill without stopping. Mine behaves this way, as another poster called it "pawing" up the hill. Works well.

It's unreasonable for consumer affairs to suggest that all priuses "stop dead in their tracks in the snow" because it's simply not true. Maybe some do, mine doesn't.

 

<div class='quotetop'>QUOTE(automatic1stdown @ Feb 4 2007, 01:39 AM) [snapback]385047[/snapback]</div>

Yes same here. Once the snow has been churned up, compacted, rutted by other vehicles, you're SOL. That's how I bogged down on Dec 31, right at the intersection with the highway where other vehicles had churned their way through.

I was raised how to properly drive in snow/ice and those "tricks" (Pretend there is an egg between the gas and your foot, no sudden steering inputs, no sudden braking, etc) just don't work with my Prius.

Some have suggested to just keep the gas pedal floored. Trust me on this, if you *really* have experience driving on snow/ice, that is a completely unnatural and contradictory way to drive.

<div class='quotetop'>QUOTE(popoff @ Feb 4 2007, 02:10 AM) [snapback]385057[/snapback]</div>

I guess that makes me a GM troll as well

 

<div class='quotetop'>QUOTE(popoff @ Feb 3 2007, 11:10 PM) [snapback]385057[/snapback]</div>

I'm specifically UNHAPPY that you guys are having this problem, and would like to see it resolved. If you need a signature on a list, just PM me. I strongly recommend you submit your issues to IIHS so Toyota will take it seriously and provide a software solution.

I call Highwheel a troller because his post is exclusively negative (unbalanced) and has a large rhetorical content, the hallmarks of a troller.

There's a big difference between anyone seeing "a" problem, and someone posting something along the lines of "and here's to add to the litany of the prius's problems..."

Looks at how many posts Hiwheel has made. Does he even own Prius?

 

<div class='quotetop'>QUOTE(priusenvy @ Feb 4 2007, 02:25 AM) [snapback]385065[/snapback]</div>

That's why I personally feel this forum is degrading into something like the GM Trucks forum, where if you bring up a problem with your shiny new expensive 2000 GMC Sierra SLT, they question everything from your "patriotism" to your manhood to your sexual orientation.

Quite frankly I could give one s*** if the badge is Toyota, Honda, Ford, or Kia, after paying money for something I expect it to work as advertised.

I have no doubts the Trac issue only exists in a minority of Prius cars, just as the stalling issue did. Well guess what, my Prius was also one of a handful that conked out in busy Winnipeg traffic in '04. If my dealer hadn't bent over backwards and all but kissed my butt, I would have Lemon Lawed it right there on the spot.

I also have no doubt only a relative handful of Prius cars have the highway "wander" or "tracking" issue, mine was borderline. It's now almost "normal" after a lot of work by the same very accomodating dealer. As far as heater performance at -25 C and colder, with a winter front it's fine; without, the pointy bits will fall off.

<div class='quotetop'>QUOTE(priusenvy @ Feb 4 2007, 02:25 AM) [snapback]385065[/snapback]</div>

Ugh, horrid stuff. May I substitute a stiff bourban or gin?

<div class='quotetop'>QUOTE(chogan @ Feb 4 2007, 07:07 AM) [snapback]385085[/snapback]</div>

Not the first time a car maker refused to admit to a problem. Eg, my former 2000 GMC Sierra with the knocking, oil burning Vortec 5.3. GM claimed the knocking and oil burning was "normal" and I was only lucky in that Manitoba has fairly strong lemon laws to fall back on.

Toyota got stuck with a similar blame-the-customer spiel when a handful of motors sludged up. For those of you who followed my threads on chasing down a weird Na reading in the used oil analysis, it finally turned out to be the absolute crap and *contaminated* dealer bulk oil. I wouldn't use that crap in a 20 year old lawnmower.

No doubt a motor oil that poor quality will cause sludging, especially in bitter cold temps like we experience up. This morning was a brisk -36 F, and sludged motors of all makes are not unheard of here. How did Toyota respond to this? Did they insist on using better oil?

No, they didn't. For a car company who purports to be so "environmentally friendly" with a flagship "green" product - the Prius - they cut the regular oil change interval from 7,500 miles down to 5,000 miles. The same exact motor in the EU - running ACEA spec motor oils - has a regular 12 month or 10,000 mile oil change interval.

I really dislike how a handful of posters here with problems are blasted by the "Prius apologists." If it's an innocent error, fine we'll all have a beer and forget about it. If it's a serious issue, then it *must* be fixed.

<div class='quotetop'>QUOTE(donee @ Feb 4 2007, 12:50 PM) [snapback]385126[/snapback]</div>

If you're running extremely high traction studded snow tires, very slight wheelspin is actually quite beneficial. The studs can claw at the surface and pull you along. I'm running this tire, called the Goodyear Nordic in Canada, and only sold at Canadian Tire retail chains:

http://eu.goodyear.com/home_en/tires/repos...p?page=benefits

I'm not a paid employee of Crappy Tire but I really sing the praises of this tire. AFAIK it's the only good thing to come out of Crap Tire. It completely transformed the winter performance of my Prius, and for that alone I'll happily put up with the moan/howl/hum from the tread.

By "spinning" I'm not talking about flooring it and cooking the tires. I'm talking about very slight but consistent - say indicated 10 MPH - spinning. And once you do bog down, you can then rock it out.


<div class='quotetop'>QUOTE(Display Name @ Feb 4 2007, 01:17 PM) [snapback]385132[/snapback]</div>

In no way am I attempting to question the snow performance of your Prius, or in any way defend a person who may turn out to be a troll.

Again, I have no doubt that only a handful of Prius cars exhibit this trait. If yours is the vast majority that don't grind to a stop, then the car is probably functioning as it should.

But ambulance-chasing lawyers aside, a small minority of Prius cars have had poor highway tracking, the dreaded "stall," lousy heater performance without a winter front, or a "traction" control system that left the car helpless with one wheel on dry pavement and the other wheel on glare ice. As stated with the sad experience I had with my 2000 GMC Sierra SLT, the car maker has a vested interest to bluff off a person with problems.

 

<div class='quotetop'>QUOTE(automatic1stdown @ Feb 4 2007, 12:39 AM) [snapback]385047[/snapback]</div>

This is basically what happened to me on Friday. I had to park in a lot that is not used much, in fact, I was the only car there. It looked like the lot had been plowed early am probably around 4 am or so. It started snowing again in the afternoon and by time I left at 3:30 pm there was a scant 1-2 inches of snow at the most. This lot is on a grade, not real steep. My car was parked perpendicular to the grade. I backed out of the spot and was pointing up the grade. I shifted into D and pressed the accelerator. I could feel the power shift between left and right front wheel and then nothing. It felt almost like the car was in neutral.

I had just read about something similar here on PC so I thought "I will press very lightly on the gas and see if that will get me up the hill". Same thing happened, power left and right and then nothing.

I then noticed a bare spot on the parking lot directly behind me. I thought maybe I could back down to there and get some traction and get out. My first attempt I did not back far enough. My second attempt I must have backed down just enough to allow my front tires to catch. I was able to start up the hill. Then I had the same power to the left, power to the right thing. I let off a bit on the gas and car slowed to about 2 miles per hour but continued to "paw" its way up the hill. As I went up the hill, I must have gotten a bit better traction because, without changing my foot position on the accelerator, the car began to pick up speed and power. I had to let off the gas so I didn't miss the turn to the driveway out of the lot.

Up until this incident, I felt my car was pretty good in the snow. I have seen the trac light many times and felt the slipping and the transfer of power as I have been going to work in the snow but never had I experienced this total lack of power. I would have had to be towed out of the lot with 1 inch of snow on the ground had I not been able to back down to the bare spot.

I am seriously considering snow tires, but after reading some posts on this thread, wonder if they would be of any benefit. I am currently running the stock OEM tires.

 

<div class='quotetop'>QUOTE(Renocat @ Feb 4 2007, 01:49 PM) [snapback]385148[/snapback]</div>

I will *strongly* suggest you look into winter tires, they really do make a world of difference. If you search for my posts regarding when I finally became stuck on Dec 31 at my hobby farm, I bogged down in a 2 foot hard drift that had been mushed up by other traffic.

In 2 inches of snow, even churned up by traffic, and especially on glare ice, my new studded Goodyear Nordic tires are invincible. I can easily dust an SUV or pickup at a green light.

Note that I didn't get winter tires because of any perceived problem with my Prius. I would expect and demand a high quality studded winter tire on *any* vehicle I drive in winter. I tired studless for awhile and they simply aren't up to maximum ice traction in bitter temps down to -40.

Most studless tires are also a poor value, as you're paying for less than half a tire. How so? Bridgestone readily admits only the first 45% of their Blizzak is the "special" Multicell tread compound. Studded tires will provide traction for the life of the tire, not just the first 45% of tread.

If you're allowed to use studded tires in your jurisdiction, this tire I can readily recommend, but AFAIK is only available in Canada as the Goodyear Nordic and is sold only at Canadian Tire

http://eu.goodyear.com/home_en/tires/repos...p?page=benefits

What I like is the tread is around 15/32 deep, and is heavily directional. Hard to believe, but in the beginning of December we had RAIN, not the -36 F like this morning. Driving on rain soaked highways, it was VERY reassuring to see the two clearly evacuated patches behind my car.

Another well-respected studded tire is the Nokian Hakkapeliitta.

http://www.nokiantyres.com/wintertyres_en

A co-worker of mine has a 2006 Range Rover HSE, and he paid a god-awful amount of money to specially import from Europe the Nokian Hakkapeliitta 5 SUV in the P255 55 19 XL size his Range Rover requires. This is a factory-studded tire that works very well on our slick intersections.

Please reconsider winter tires

 

<div class='quotetop'>QUOTE(Renocat @ Feb 4 2007, 10:49 AM) [snapback]385148[/snapback]</div>

I will submit that your hesitation is the result of the Hiwheel troller.

The stock tires are worthless on snow and ice. That's pretty much universally agreed upon in priuschat.

I put on Michelin X-ice and while it is possible for me to get stuck, it's only in a particular kind of snow. Mind you, I've gotten my 4wd with front and rear lockers stuck also.

With the X-ice winter tires, I've been able to cope with all the snow storms Colorado has gotten except for one, but then again I just left the Prius in the garage and didn't even try.

Unless you're driving deep in the cascades, there is nothing wrong with Prius (at least nothing wrong with my 07) as long as you have good winter tires on. The TRAC "feature" does take some getting used to, there is no denying that.

 

<div class='quotetop'>QUOTE(donee @ Feb 4 2007, 11:50 AM) [snapback]385126[/snapback]</div>

Thanks for your input but I have to differ.

On several occasions, the TC in my '05 has kicked in and left me without any traction. The total shutdown has occurred on loosely packed gravel driveways in the middle of the summer on two different driveways with only a slight pitch (I wound up having to backup the driveways.) There was no possible way that the gravel could have lifted the body of my car enough make the wheels spin. The problem is not that the wheels are spinning, but the exact opposite. TC cuts in when it detects a spin and shuts down all propulsion. In my original post, which followed the post of a fellow Priuschat poster, the TC cut in and the engine shut down in less than a couple of inches of snow. Once again, the snow was no where deep enough to lift the body of the car.

BTW, as stated in a in earlier message, the thought also crossed my mind that Hiwheel might have been trolling.

I'm happy to see that this thread has evolved into a serious discussion of the problem some of have us have been encountering.

 

<div class='quotetop'>QUOTE(Display Name @ Feb 4 2007, 01:33 PM) [snapback]385166[/snapback]</div>

Once again, I must respectfully differ.

I'm using Michelin winter tires (I don't remember specifically which model they are), grew up in the northeast, and have attended an Audi sponsored ice driving school in Germany. I'm not bragging, I'm only offering that I do have some experience with driving on ice and snow, as well as other adverse conditions.

Please respect the fact that several of us have been experiencing the problem and that while I fully agree that snow tires do make a great difference in Prius' performance on snow and ice, they are of little use when the car hits a snowy, icy, or any other loosely packed surface, the wheels spin, TC cuts in, and both methods of propulsion shut down.

 

<div class='quotetop'>QUOTE(popoff @ Feb 4 2007, 12:03 PM) [snapback]385172[/snapback]</div>

I don't doubt your driving skills. I'm assuming, maybe at my own peril, that people who live in snowy areas should have decent winter driving skills.

It may be useful to make a distinction between the cars that have the problem and the cars that don't. I understand '04 and '05 tend to have the problem, and I know my particular '07 doesn't. Is there another way to do it?

I think it's important to make that distinction because it's possible that Toyota has fixed the problem after year X, and we shouldn't be scaring people off who might otherwise get a car they'd love. I make suggestions based on my experiences with the latest version of the car.

 

<div class='quotetop'>QUOTE(Display Name @ Feb 4 2007, 02:17 PM) [snapback]385181[/snapback]</div>

Mine is an '06, purchased in July of last year.

 

<div class='quotetop'>QUOTE(Display Name @ Feb 4 2007, 12:17 PM) [snapback]385181[/snapback]</div>

I think it is important that a distinction be made, and perhaps the problem can be isolated. I don't know if it has anything to do with the software version of the TRAC, but there clearly seems to be some cars that essentially fail (shutdown) when faced with any low traction situations but this is not true of all.

Case in point: I decided to wash my car today, as it finally warmed up here to a balmy 36F. I went to one of those automated, drive through, brushless places, and as I was driving through the "blow dryer," I was suddenly stuck. The front tires were spinning on the ice that had built up directly outside the exit. I had a big pickup coming in behind me, and really didn't feel like asking for a push, so I floored it. Upon flooring it, the traction light came on, but the tires spun. I alternated flooring the accelerator and backing off. The car rocked several times, and was free of its icy trap, tires spinning the entire time. I glanced back to see what I was stuck in, and it appears that there are two deep impressions in the ice, polished to a high shine by all the cars coming through the wash.

Now, obviously, the traction control "feature" or "problem," depending on your point of view, does not affect all Prii. By the way, mine is an 06 with TRAC and VSC. It has 13500 miles, and is still host to the awful stock goodyears. I am yet to experience any of the TRAC problems faced by so many, and I know this is not due to any miraculous driving skills on my part.

 

having had an 04 and an 06, i wished i would have had the opportunity to see how the 04 reacted in snow. but in the two winters i had the 04, we had no snow so dont know.

i do know that i tried doing donuts at a friends yard (its a big field, not a lawn and he was in the car with me at the time) in the 04 and really couldnt do anything especially if from a standing start. with a running start, there was very little fishtailing and no real sliding at all. the 04 did not have VSC

on my 06, we had snow and i experimented with skidding and icy hill climbing and the power pusled to the wheels. the first time i tried it was very cold about 20º and 2 " of snow. this hill is my driveway and and has a short section that is banked about 20º or so. pretty steep. i purposely hit this section doing about 3 mph. it bogged down almost immediately. if hitting the section at 10 mph or more (normal speed for me anyway, my momentum comes close to letting me make the top which is only about a 50 foot section but not quite and after i stop, the pulsing only caused me to slowly slide DOWN the hill.

i then waited until the sun hit the driveway, then tried it when it was just at freezing about 33º and same basic thing happened, but the pulsing actually allowed me to slowly climb the hill albeit a few inches at a time so the ice was actually melting under the tires. but the tires still turned. one thing i noticed is that it didnt matter how far the gas pedal was pushed, the pulsing remained the same. hitting the hill at 10 mph, i made it up easily with TC flashing all the way.

now i have the OEM's and do not plan on getting anything else. just dont need them. i have chains for ski trips and the like so im good. i do wish that TC could be disabled or have a user setting that will allow a level of slip while still protecting the system with computer control.

its nice to have the luxury to make that decision, if i lived in the northeast or canada, i would be changing the tires quick. i do notice that additional tire pressures combined with narrow footprint simply does not lend to surefootedness.

 

<div class='quotetop'>QUOTE(popoff @ Feb 4 2007, 03:45 PM) [snapback]385167[/snapback]</div>

Hi Popoff,

It not possible for the traction control to detect slippage, if there is no slippage. If there is slippage, what good is further slippage ? The trick to slippery surface driving is to never slip in the first place. Chains and studs only help improve the accelleration possible on the slippery surface. If one wheel slips, that puts the traction demand for the whole vehicle on the single other drive tire for a 2WD car. If that other tire can not deliever twice the traction demand as previously, when the first tire slips, it will slip. When both tires slip in the Prius apparently the power is killed (I have not been in a two tire accelleration slip situation in my Prius yet) and the car slows. In a standard car the power is not killed, but the car slows all the same. The two cars are driving on the same interface between the tires and the slippery surface and its that interface the energy must flow. So, one must drive at an acceleration where one tire on the average surface is sufficient to move the car.

How do you know that another car would have done better in that specific situation? Not the specific spot, the specific spot in the same condition? Is the gravel driveway condition more worn than previously? You may be focusing on the apparent difference - the Prius, and not the important difference, the road surface. As the road surface just happens to be in the same spot as its always has been, does not mean its the same. Is the gravel base as thick as it used to be, or is there hard dirt under a single layer of gravel - a ball-bearing situation? Is the gravel layer thick enough to support the weight of the car when the underlying dirt is wet? Or is the gravel just pushed down into the mud? Has drainage changed? Or were you caught unawares and drove at an accelleration that required vehicle acceleration demand that was more than one tire could provide on the surface ?

I saw one post about a Ford Focus on the similar surface that the Prius had difficulty. But the bulk of the comments are not direct comparisons. This is how I know my SL2 was good in snow. On one occaision the main highway was a dead stop in the snow storm. I decided to get off and take the two-lane highway home. It was unplowed with 6 inches of fresh snow and only a few other cars. At the stop lights, the car was able to out-accellerate more than half the other cars. One car that was really bad was a Chevy Monte Carlo. So bad, I thought it was rear wheel drive. The cars that were good were an original Jeep Cherokee, and a Camry.

Another thing to point out is the torque change capability of the Prius at slow speeds is nearly instantaneous. Its not like an automatic transmission, with an engine, fly-wheel, and large dead roating inertia of the torque-converter. Quickly blip the throttle on the automatic transmission car and the engine takes a few hundred ms to come up to speed as it fights the inertia of the fly-wheel and torque converter, pistons, rods and chrank shaft, and some more time for the fluid in the torque to transfer the torque to the gear box. Do that in a Prius, and the motors dump full torque to the road in less than 100 msec, and the torque has no cushion but the stiff cold tires. The Prius can follow the actual blip of the peddle, where a standard car is so slow in reacting, it low-pass filters the blip, and results in allot less peak torque to the wheels over a broader time. The Prius pedal is more like a servo motor system. Quickly blip the throttle on the Prius on snow, and it probably will slip both tires, and the power be retarded before the blip even reaches its peak pedal position.

What does this mean for the slippery surface driver? It means bring the pedal up slower than in a standard car, because there is no need to compesate for the slow reaction time of the standard drive train.

 

<div class='quotetop'>QUOTE(donee @ Feb 4 2007, 03:31 PM) [snapback]385212[/snapback]</div>

Thanks for well thought out and comprhensive response.

I knew the use of the word "slippage" might come back and bite me in the a*s , but I'm going out to wash the "electromobile " and I didn't want the temperature to start dropping below the current 25F before I'm finished with the wash and application of Zaino Gloss Enhancer. (If you ever build a house, be sure to run a hot water supply as well as the conventional (sp?) cold only. Hot water makes a world of difference.)

Being in somwhat of a hurry, I can only add another quick thought which once again might not be descriptive of what I really mean to say. Perhaps you can help fill in the blanks? In the gravel scenario, several other cars had completed their trip up the driveway before my attempt. I tried several approaches, first gently applying power but there was none to be had. Then I backed down to the pavement, got a running start, and still bogged down in the same place which, at this point, was somewhat dug out. At that point, I was completely frustrated and chose to back up the driveway, a practical but not so elegant arrival. I really should not have used the word slippage, rather a loss of traction, perhaps a small but significant difference.


The same loss of traction is what stopped me cold in the parking lot. Hitting the small snow ridge once again caused a loss of traction, rather than causing slippage, which thenresulted in both drive systems shutting down. Dead in the water with rapidly approaching traffic :huh:

Please let me know what you think about the substitution of the word "traction" for slippage. Perhaps I'm still not conveying what I'm attempting to say.

BTW, I'm in no way trying to compare my experience with TC to that of others. My brother also has a Prius, purchased in March '05, within two weeks of mine, and has the same complaint. He deals with a much more cooperative dealer than I do, so I'll suggest to him to have the dealer reflash his ECU and see if that makes a difrerence.