Serious concern haunts me

<div class='quotetop'>QUOTE(TonyPSchaefer @ Jan 18 2007, 09:36 PM) [snapback]377546[/snapback]</div>

Yeah, definitely skip that one!! its tough to watch from any perspective. Just try to keep a positive attitude dude, i read your post about the mud incident. Featue or failure, it is what it is. i usually have to drive our 4WD truck when it snows here anyway. good luck! :lol:

 

You live in upstate New York. Buy snow tires! Problem solved.

 

<div class='quotetop'>QUOTE(Miz @ Jan 18 2007, 10:29 PM) [snapback]377543[/snapback]</div>

Miz, there's plenty of threads on here with people discussing driving the Prius in the snow. Some with steep driveways. One even from Norway: http://priuschat.com/index.php?s=&show...st&p=374300

Just do a search on the word "snow" and you'll find plenty of suggestions.

If snow is a huge issue for you, you can always consider upgrading your tires. I'm little surprised your "tech" didn't suggest this.

 

<div class='quotetop'>QUOTE(R32 @ Jan 18 2007, 09:38 PM) [snapback]377570[/snapback]</div>

Other old-school advice applies to hybrids as well, like carrying some sand or salt. And years ago, I kept a gripper in my trunk. It was a plastic device you place under a tire to climb up onto to pull yourself out of a rutt.

 

I live in Northern Michigan, and drive my Prius on snow covered hills all the time. It does just fine, and in fact is one of the better winter cars I have owned, which includes a Jeep CJ-5, a Subaru, and a 4wd Ford Aerostar. The 4wds have a little better traction, and the Jeep had a lot better ground clearance, but none of them were as well mannered on slippery roads. The Prius just tracks down the road with no fuss or bother.

The first thing I did with our new Prius was to go out and buy some real tires. The stock ones are useless in snow. Second thing is to play with your new car and get a feel for how it works. The traction control is different, but workable once you understand it. In a low traction situation such as a snowy hill, you mash the gas pedal all the way to the floor and just hold it there. It's counter-intuitive when you are used to normal cars without traction control, but the Prius won't let the wheels over-spin. By pressing the pedal all the way to the floor, you are telling the computer to give it a little harder try. The Prius will spin the tires, but in a controlled fashion, much like low-low in a Jeep.

Tom

 

<div class='quotetop'>QUOTE(Miz @ Jan 18 2007, 07:29 PM) [snapback]377543[/snapback]</div>

I realize that you had a terrible experience with the prius in the mud, but I think you are worrying a bit too much. I live in a city (hah!) in the mountains in Montana. We get a fair amount of snow, but mostly alternating mild and bitter cold, which results in glare ice streets. It just so happens, that Butte (said "city") also has some extremely steep streets, many of which I must traverse daily on my way to school. I have been nothing but impressed with the prius in the snow. I still have the original tires, and I am yet to have a problem. I drive it every day, even in as much as 6"-10" of snow on top of ice. In addition, I have on a couple of occasions driven the prius up to Discovery Ski Area, and had nary a problem (aside from my driving too fast and crashing into a snow bank, but no harm done). If you are really concerned, which you seem to be, I would suggest putting a set of snow, perhaps even studded, tires on your car. They make a tremendous difference. Good luck.

 

When it snows (IF it snows this year lol) I actually prefer to drive the Prius. I find it an excellent snow car. My Lexus is FWD with VSC too, but the Prius is better. I had an Explorer beforehand, of course the Explorer was the best but I would comfortably drive the Prius on all season tires up to 5-6 inches of snow.

The issue you're facing comes from the fact that the TRAC on the Prius is a little bit oversensitive because wheel spinning is very dangerous for the CVT and the hybrid system. Thats what keeps the wheels from spinning when you get stuck.

Now, it is entirely possible that any car would have gotten stuck in that mud. Mud is MUCH more slick than snow and only gets gooier with heat. So it gets up in the tread of your tires and fills them in real quick.

 

<div class='quotetop'>QUOTE(qbee42 @ Jan 18 2007, 11:14 PM) [snapback]377581[/snapback]</div>

Thanks for the tip -- I would never have thought to do that. Not in a million years. If it ever snows again in Virginia I'm definitely going to try that out.

 

The OP needs an aggressive snow tire. Period.

If the Prius allowed us to spin the wheels there is zero guarantee that we would be any better off. Sliding friction is less than static friction, which is why the best thing to do in slippery conditions is avoid wheel spin. Some cars (Volvo for one) even offer a "winter mode" that intentionally limits torque by starting you off in a higher gear specifically to prevent wheel spin. I've been forced to test this principle many, many times and the sound of spinning tires is usually the end of my attempt to get un-stuck.

Michelin makes an excellent snow tire, as does Bridgestone (used 'em this morning). Gislaved Nord-Frost tires are incredible but a bit pricey and difficult to get.

 

I have to agree with the others. The prius is actually the best snow car I have owned. With ABS, Traction and VSC it handles better then my other car. I'm surprised how well it does.
/Robert

 

<div class='quotetop'>QUOTE(brick @ Jan 19 2007, 11:45 AM) [snapback]377731[/snapback]</div>

The physics behind traction is quite complex. While it is true that static friction is higher than dynamic friction, friction alone does not translate to driving force. For example, a car parked on dry pavement has great friction, but no driving force at all. Driving force is a function of friction and torque. Maximum driving force under most conditions occurs with a small amount of spin. This is because the extra applied torque more than makes up for the reduction in friction. Trains use this technique all the time on steep grades, where a limited slip traction control system allows the wheels to slip at a rate calculated to provide the best driving force. Automobiles have a problem with this technique because the slip is not controlled, and the non-linear friction curve allows the wheels to spin faster and faster with the same amount of applied torque - that's where you get classic wheel spin.

An additional complication occurs with snow and mud, where phase changes and mechanical separation is produced by heating and pressure, which causes liquid water to form, which in turn lubricates the traction surface. The exact point at which this occurs varies widely with environmental conditions, which is why almost anything will get stuck in wet mud or wet, dense snow.

A third factor affecting vehicles with powered front wheels is the ability of the front tires to contact fresh ground while spinning. A controlled spin will allow for a fresh bite when the front wheels are turned from side to side. We often used this technique when driving our old Jeep CJ-5. In low-low, the tires would slowly spin, allowing the driver to turn the wheels back and forth and slowly walk the Jeep up a hill. It didn't always work: sometimes you just dug a hole and then you were really stuck, but often you could get enough fresh grip to make it up.

Tom

 

I've had good luck with this car in the snow. But mud is something else. I used to live on a dirt road with a fair sized hill that under the right weather conditions would get very muddy. One time it took three tries to finally reach the summit. On the final try, after backing down the hill twice (scary), I took the longest run possible with accelerator to the floor all the way (as I had done before) and made it to the top. On the prior two tries, on hitting the muddier parts, the car's engine would just keep slowing RPMs 'til the car (engine) would just stop running and not even try. Very frustrating. There was nothing I could do but back down the hill and try again. Had I not made it on my final try I'd have been stuck at home for a couple of days.

This is not snow tire country (even though this year we've had record snows), so had I continued to live there in Placitas I'd have probably purchased another kind of car (another Audi A4 Quattro maybe). The mud can happen any time of the year around here so snow tires were not the answer.

If your mud occurs primarily in the winter, snow tires are probably the only viable approach to addressing this problem.

 

<div class='quotetop'>QUOTE(Ken Cooper @ Jan 19 2007, 12:54 PM) [snapback]377778[/snapback]</div>

I had a similar experience with gravel at the Red River Gorge in Kentucky. Your description is exactly what happened to me, except with the added sound of gravel. The traction control kicked in and out as the tires slipped, going "rrmmmph, rrrmmph, rrrmph..." Only a mad dash at full throttle, bouncing over the ruts, got us to the top. In fairness to the Prius, I had similar problems with a Ford Focus on a previous trip. The Ford lacked traction control, so it didn't shut down the power, it just sat there and spun.

Tom

 

<div class='quotetop'>QUOTE(Miz @ Jan 18 2007, 09:29 PM) [snapback]377543[/snapback]</div>

I knew a guy who put in a system that heated his driveway. All he did was flick a switch in the house and no snow or ice ever accumulated on the driveway. If I were in your situation and had lots of $$$ I would definately check it out.

 

<div class='quotetop'>QUOTE(Miz @ Jan 18 2007, 09:29 PM) [snapback]377543[/snapback]</div>

While I live in CA and don't generally see much snow on the road, I'd guess that the suggestion that you should buy good winter tires is a good one.

That said, the issues with the Prius, and traction, and traction control, are perhaps my most serious qualm with the car. Regarding the last, it's just not sophisticated enough to be more trouble than it's worth, in my opinion. It cuts off the power too abruptly and to too great of a degree. It doesn't seem to be proportional, it's either you're getting normal power to the wheels or it throttles the car back to something just over idle...with not much in between.

Worse, it's really funky how it flips from power to no power to power to no power and back again, sometimes a few times per second it seems...which only makes the traction issues worse, not better. I mean, the key to good, fast, safe driving is to make sure the tires have adhesion at all times (rally-style drift driving and racing on ice, etc., are different of course)...which means that it's important to be *smooooooooooth* above all else, I think...and the car is completely counter to this idea sometimes.

It would be great if I could use the throttle to balance the car's traction right on the edge of the traction control...but it's simply impossible to approach that limit with any degree of finesse. I'm still playing with it, purposely spinning the wheels in different scenarios (just to practice, and there is actually a ray of hope I'm finding) but it continues to feel a lot like a workaround to me.

It's okay, though, there's yet to be a car that I haven't enjoyed learning to drive (regardless of how many "challenges" it's reputed to have).

 

<div class='quotetop'>QUOTE(Pinto Girl @ Jan 19 2007, 02:40 PM) [snapback]377862[/snapback]</div>

Engineers refer to this kind of protection as fold-back limiting, which means that once the limit is reached, the system drops back or folds back to a much lower level. This makes sense for some types of protection, such as circuit breakers and fuses. With circuit breakers, you want the power turned off when a circuit fault occurs. It doesn't make sense for traction control. For traction control, it makes more sense to limit the wheel speed to a safe level but still let the wheels slip, instead of chopping the power completely. Toyota did this a little bit with the 2006 models, but they could do a lot better job.

Tom