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To drive off uphill on a road with snow

Hi

I live in Switzerland. Sometimes in winter I have to drive off uphill
with snow on the road. My father owns a Lexus with rear wheel drive and
often has problems in winter. I own currently an Audi with front wheel drive
and never had any problems in winter.

I'm really interested in the Tesla Model S, but I'm not sure if the
rear wheel drive has problems too in winter.

Bye

The reason for this difference is due to weight distribution. On ICE vehicles the majority of the weight is in the front which is why front wheel drive cars do better than rear wheel drive. But the Model S does not have this disadvantage and has its weight spread evenly. My assumption is that it will be nearly as good as a front wheel drive vehicle and will definitely be safer in a skid situation as the front wheels will not be trying to slow you down and possibly losing traction.

the combination of low center of gravity and traction control should allay your fears. here's a nice video of a former roadster and current model s owner driving after a big snow storm in boston. the rear wheel drive was a little concerning for me as well. but, after looking into it, i don't have any concerns.

http://www.youtube.com/watch?v=wCGBOQO1bLw

silvio.k, you may want to read this thread, with links to a number of older threads that discuss driving on snow, RWD vs. AWD, cold weather operation of all components, protection from salt and water, and more:
http://www.teslamotors.com/forum/forums/cold-weather-operation

No big problem with snow but if you stay stuck in snow you must leave the car there until snow melt (no tow hook) or probably void your warranty.

No won't void the warranty - rangers can service the stranded vehicle in the snow and you can retrieve in the spring with all being well. Gotta love those rangers...

That was me in Boston with that video. Indeed the Roadster did really well in the snow. I have zero concerns with the Model S in the snow.
I took the Roadster up my hill when I saw another truck stuck spinning their wheels. The road had glazed over. I had no troubles getting up the hill.

I learned to drive and have "always" driven rear wheel drive cars. Winter driving?? Not an issue when you remember to keep your brain engaged. And in the slickest of conditions such as Ice it does not matter which or how many wheels are driving. The proof will be in the median strips and ditches of America this winter. Think not? just count the front drive cars in the ditch or otherwise stuck this winter lol!!

Four wheel drive is obviously the best solution to icy conditions, but Model S rear wheel drive with that low CoG should make it quite good winter car. Moreover drive setup is like 5% compared to the tires used. Good tires make any car good winter car and bad tires makes them bad. Pay attention to tires you choose and their condition after.

Reason why four wheels is best is simply the fact that four wheels allows less force / wheel to get same outcome, thus lessening slip. Also if one tire gets stuck (or is slipping) you have three instead of one to get loose from that stuck.

OTOH, with four wheels when you lose control you really lose it. That means you find yourself much deeper into ditch than you would with any of the two wheel drive options.

Traction Control is just as big a factor. Most winter driving stupidity and accidents I've seen involve over-driving the drive tires, and making ice out of snow on the go. People not used to winter driving can't seem to get the idea that more gas/pedal = less traction, and less pedal = more traction.

@Superliner, Timo

Reminds me of a friend who purposely went off road into an area no vehicle should go thinking he was invincible with 4WD. He wasn't :)

If you go into a snow bank, and the battery pack is sitting on a solid pack of snow, will the temperature control system for the battery pack tend to melt the surface of the snow (through the aluminum casing) and tend to help the car slide downhill (the battery pack is flat)?

Might be good if you just need to get back onto the road from a large snow bank. All you'd have to do is clear the wheels a bit.

On the other hand, if the road is falling off to the side....

Either way, it would be good to know what to expect.

I'm not going to risk my new Model S in the snow where I live (Seattle). It's very hilly, no roads are ever plowed because snow is only once a year, and most other drivers are very inexperienced and drive dangerously. I'll just drive my wife's Volvo to work those days!

"other drivers are very inexperienced and drive dangerously"

It shouldn't be funny, but somehow it is: in here we have snow and ice every year sooner or later in October and sometimes as early as late September. This is to be expected, but somehow every god d*mn year at first ice we have a pileup. Somehow that ice manages to surprise those "other drivers" every year.

I too would be reluctant to take my new car onto road at first snow. Later when those other drivers are already repairing their cars it would be relatively safe to drive it.

Yes; wait for the first big wave of ijits to take themselves out of circulation! Good plan.

Yes there are people who don't recall how to slow down with the first snowfall but what many don't realize is the first snow of the season is actually much more slippery than later snowfalls due to the warmer temps and warm roads that haven't been cooled from exposure to cold temps for a long period of time. Just take a handful of snow in your hands and see how much friction there is when you first pick it up to when it starts to melt in your hand and you get the idea. Since it is closer to melting it forms ice with water on it quickly from warm tires.

In Seattle we only get the 'first snow.' Even if it snows again it's usually been warm in between.

It's astonishing how short peoples' memories are. Back in nw Ohio, I saw it every year. First snow, ijits ahoy! Plenty of fender benders, and a few in ditches. Then first ice: repeat with more serious accidents, multicar pileups, cars wrapped around poles, etc.

Now in Seattle area, it's déjà vu: except when the first fall rain happens, it's almost like they haven't seen rain before. Then snow or ice -- disaster.

Same with Minnesota. You'd think of any state in the 48 contiguous, Minnesotans would take the first snowfall seriously, but no.

In my experience;

AWD + Winter Tires = Best Option (not entirely stress-free but pretty close)

FWD + Winter Tires = Good, not great. (unplowed hills can be a problem if your traction control is too aggressive)

RWD + Winter Tires = Acceptable. (you can drive with some confidence but stress is still high because you may plow straight ahead over the next turn)

UPSHOT: Drivetrain is secondary. Good winter tires are non-negotiable.

Next year's "Model X" is an all-wheel drive variant on the Model S; perhaps it would better meet your concerns. I'll bet it can power up your favorite alp all day long.

Dave;
The Perf version of Model X only.

Mayhemm,

Vehicle Stability Control minimizes the difference between all three drivetrain choices. Studless winter tires from a tier one tire manufacturer are very important.

jerry3;
Does SC and/or TC deal with the "plowing straight ahead over the next turn" issue?

My own one non-winter 'free-sliding' experience occurred with a FWD Civic in the mountains. Came to a left turn, facing a steep drop-off, and the road was lubricated with small gravel. The car started to straight-line. My cerebellum took over, and I went off the gas, then "blipped" front wheels to get back in contact with the pavement. That sweet little car jerked me around the corner, back in control.

Like they say in combat, there's nothing like getting shot at -- and missed!
;)

Brian,

Yes, Stability control deals with that. Very well in fact. Traction control does not deal with that at all, it's about tire spin. They are really two separate systems.

I have it in the Prius and it's almost impossible to make it misbehave. Even if you get it totally sideways (meaning that you're driving like a complete idiot, or are just trying to test the limits) it corrects itself (regardless of whether it's sideways because of plowing straight or sideways because of rear end overtaking the front end).

From the manual:

The followings are two examples that can be considered as circumstances in which the tires exceed their lateral grip limit. The Enhanced VSC system is designed to help control the vehicle behavior by controlling the motive force and the brakes at each wheel when the vehicle is under one of the conditions indicated below.

- When the front wheels lose grip in relation to the rear wheels (front wheel skid tendency).
- When the rear wheels lose grip in relation to the front wheels (rear wheel skid tendency).

To determine the condition of the vehicle, sensors detect the steering angle, vehicle speed, vehicle’s yaw rate, and the vehicle’s lateral acceleration, which are then calculated by the skid control ECU.

1) Determining Front Wheel Skid

Whether or not the vehicle is in the state of front wheel skid is determined by the difference between the target yaw rate and the vehicle’s actual yaw rate.

When the vehicle’s actual yaw rate is smaller than the yaw rate (a target yaw rate that is determined by the vehicle speed and steering angle) that should be rightfully generated when the driver operates the steering wheel, it means the vehicle is making a turn at a greater angle than the locus of travel.

Thus, the skid control ECU determines that there is a large tendency to front wheel skid.

2) Determining Rear Wheel Skid

Whether or not the vehicle is in the state of rear wheel skid is determined by the values of the vehicle’s slip angle and the vehicle’s slip angular velocity (time-dependent changes in the vehicle’s slip angle). When the vehicle’s slip angle is large, and the slip angular velocity is also large, the skid control ECU determines that the vehicle has a large rear wheel skid tendency.

When the skid control ECU determines that the vehicle exhibits a tendency to front wheel skid or rear wheel skid, it decreases the engine output and applies the brake of a front or rear wheel to control the vehicle’s yaw moment. The basic operation of the Enhanced VSC is described below. However, the control method differs depending on the vehicle’s characteristics and driving conditions.

1) Dampening a Front Wheel Skid

When the skid control ECU determines that there is a large front wheel skid tendency, it counteracts in accordance with the extent of that tendency. The skid control ECU controls the motive power output and applies the brakes of the front wheel of the outer circle in the turns and rear wheels in order to restrain the front wheel skid tendency.

2) Dampening a Rear Wheel Skid

When the skid control ECU determines that there is a large rear wheel skid tendency, it counteracts in accordance with the extent of that tendency. It applies the brakes of the front wheel of the outer circle of the turn, and generates an outward moment of inertia in the vehicle, in order to restrain the rear wheel skid tendency. Along with the reduction in the vehicle speed caused by the braking force, the excellent vehicle’s stability is ensured.

In some cases, the skid control ECU applies the brake of the rear wheels, as necessary.

There's more and some diagrams, but this should give you the general idea.

Wondering about that specific situation I described, where the fronts are suddenly on ball-bearings (and of course were the driving wheels!). Would SC have duplicated my maneuver? Or interfered with it?

Duplicated it but much faster than you could have done. What you're describing is "When the front wheels lose grip in relation to the rear wheels (front wheel skid tendency)."

Good to know! But the downside to all this safety stuff, of course, is the homo sap need to push the limits. I think it's been observed that people quickly take them for granted, and then try to make it exciting anyway. Which means leaving the possibility of gruesome death on the table ...

Brian,

In this universe there is a race between the engineers trying to create idiot-proof safety systems and the universe creating bigger idiots. So far the universe is winning.

+1 jerry3
With the added point that legislators often seem to push for idiot-proof solutions for problems that may not exist.
see also http://www.darwinawards.com/darwin/

@rmitchum

Ironic, since IMO legislators are some of the best examples of idiots.


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