Taycan 4s parked on snow rolling forward - how why and wtf??

[NaiM5]

Sorry to hear about these two snow Taycan runaways. Thanks for the heads up.

Something to consider: Several years ago when I owned a Model S P85D, I wasn’t able to stop coming to a light after driving in snow. It scared the heck out of me. I kept slamming on the brake pedal until finally the friction started, half way thru the intersection.

It occurred to me that there was ice/snow build up in between the pad and rotor, and given how electric cars decelerate via regenerative braking, the rotor/pads never got hot enough to melt the snow/ice. SNOW ICE Brake failure! I posted about it years back on my social media that when driving electric, it is important to cycle thru your friction brakes once and a while. I also wrote Tesla about the concern.

Perhaps a clue on what could be happening here...

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[PanameraFrank]

The simplest cause would be if you stopped the car, the hill hold automatically turned on, you turned off the car, and walked away. Once the hill hold also turned off (it takes several minutes for the Taycan to fully shut off) the car rolled down the hill. Doesn't mean that's what happened but it's the simplest way for this to happen.

Or the drive was entirely ice, some people/towns accidentally turn their drives into ice when trying to prevent/clear snow, in which case anything would have slid down as the residual warmth of the car dampened the wheels & melted the top layer directly under the car.

Sucks this happened. Just my 2 cents.

 

[REIL]

Hi All

Just had a rather scary near miss and felt the need to warn people. Im a UK 4s owner, loving the car which Ive had for 6 weeks (pre cool issues aside).

We have had a classic UK snow fall overnight around a few cm's which is enough to decimate the town!! Drove my Taycan to the office and parked on a very slight incline, handbrake engaged. One foot out of the car and on the ground and the rolling starts!! A 2 ton car rolling on 3-4 cm of snow. Managed to get back in and pulled up a few feet away from a wall.

How the hell has this happened? Imagine this occurring on a sharp incline in a town centre?

Is there no anti-roll safety feature? My wheels were turning so I was told by a witness, meaning they werent locked or fixed by the handbrake.

I would definitely avoid parking this car on an incline in snow. Of more concern is the question as to how the car would behave in traffic facing downhill when stationary in these conditions?

Any thoughts welcome particularly from any UK dealers who may be aware of this issue.

@Martin
Glad you are safe.
Replied to this on the other thread. Here is the link.
https://www.taycanforum.com/forum/t...now-bad-day-at-the-office-pt2.3394/post-46753

 

[bosch88]

Sorry to hear about these two snow Taycan runaways. Thanks for the heads up.

Something to consider: Several years ago when I owned a Model S P85D, I wasn’t able to stop coming to a light after driving in snow. It scared the heck out of me. I kept slamming on the brake pedal until finally the friction started, half way thru the intersection.

It occurred to me that there was ice/snow build up in between the pad and rotor, and given how electric cars decelerate via regenerative braking, the rotor/pads never got hot enough to melt the snow/ice. SNOW ICE Brake failure! I posted about it years back on my social media that when driving electric, it is important to cycle thru your friction brakes once and a while. I also wrote Tesla about the concern.

Perhaps a clue on what could be happening here...

I think this makes the most sense since most of the braking is by the regen motors so the pads are slowly icing up.... once parked, the iced up pads are pressed against the rotor... without much friction between the pads and rotor or the ice starts to melt it would create a slight void, the car will start to roll... pretty scary sh*t.... makes me wondering about just normal driving in the snow / ice without the pads getting used much, will affect sudden stops with the pads... might need to do some "safe" hard stops once in a while during cold weather to heat them up...

 

[Dlurker20]

This is an interesting post since I had the exact opposite scenario. We had several inches of snow dumped atop ice, I’m on the downslope on the road, my car is holding fine while cars around me are sliding and can’t make it up the hill. Oh I slid when I came to a stop. But once held it was rock solid (and I did have to put it in park to go help a stuck BMW). I walked away impressed as hell with the car’s handling in snow/ice...quite the opposite of it rolling when it should be stopped. Yes it slides on ice but it’s better than any car I’ve had before, and it definitely has never rolled while in park.

 

[Scandinavian]

I was informed by a witness the wheels were turning not locked as youd expect. I didnt see this as I was in panic mode trying to stop the car.

There is cctv footage Im trying to get hold of.

would it be possible that the witness saw the front wheels turning but the rear wheels were locked. I guess the parking brake only applies to the rear wheels as probably the parking lock does as well?

really interesting if you can get cctv footage

 

[NaiM5]

I think this makes the most sense since most of the braking is by the regen motors so the pads are slowly icing up.... once parked, the iced up pads are pressed against the rotor... without much friction between the pads and rotor or the ice starts to melt it would create a slight void, the car will start to roll... pretty scary sh*t.... makes me wondering about just normal driving in the snow / ice without the pads getting used much, will affect sudden stops with the pads... might need to do some "safe" hard stops once in a while during cold weather to heat them up...

Yes, I made sure to do brake checks periodically. It's a real issue with these regeneration brakes...

 

[Aigle836]

Not that many as heavy as the Taycan (2305 kg)..... Heavier than the Panamera (1870 kg) and Cayenne (2215 kg). Same as Range Rover (2360 kg). Bet not that many of the Range Rover / Cayenne are equipped with slick performance summer tires, most likely they will be on all-season tires.

Another point. ICE AWD cars will have all 4 wheels locked on park. FWD cars with the car in gear and the parking brake applied will also have all 4 wheels locked. My guess is that on park with the Taycan, only the rear wheels are locked. Front wheels will remain free. So on a slippery incline there is only the 2 rear very slippery high performance summer tire holding a very heavy car. Much heavier the an ICE RWD only car. On some pictures I have seen on another post, there were skid marks from rear wheels (lock and slipping) but not from the front (free wheels).

Either way here in Canada I change to my winter tires when the temperature drops below 7°C. Way too dangerous driving under that temperature with high performance summer tires.

 

[Morchman]

Another point. ICE AWD cars will have all 4 wheels locked on park. FWD cars with the car in gear and the parking brake applied will also have all 4 wheels locked. My guess is that on park with the Taycan, only the rear wheels are locked. Front wheels will remain free. So on a slippery incline there is only the 2 rear very slippery high performance summer tire holding a very heavy car. Much heavier the an ICE RWD only car. On some pictures I have seen on another post, there were skid marks from rear wheels (lock and slipping) but not from the front (free wheels).

Either way here in Canada I change to my winter tires when the temperature drops below 7°C. Way too dangerous driving under that temperature with high performance summer tires.

I think this is a very plausible explanation. It remains a frightening prospect that these cars may carry such a risk.

I would say for the benefit of our North American brothers that it is not common for UK drivers to switch to winter tyres because our climate just doesnt justify it. However Im now going to sort this and order some.

 

[Aigle836]

I think this is a very plausible explanation. It remains a frightening prospect that these cars may carry such a risk.

I would say for the benefit of our North American brothers that it is not common for UK drivers to switch to winter tyres because our climate just doesnt justify it. However Im now going to sort this and order some.

Well it is 1 possibility. I have steep inclined driveways and when there is bad weather (mix of snow, rain and freezing rain), even my Cayenne Turbo with winter tires will slip down if I do not put some small pebble stones under the wheels (and all 4 are locked). They sell that by 50 lbs bags here and I always carry one in the trunk in winter. I f1nd it is better as sand and salt will wash over if there is rain.

You can take a used can of coffee with cover and keep that or sand in the trunk in winter. Yon can then put it front or back of the rear wheels when you park (depending on the side of the incline). You can use sand but cat litter or fireplace ash are also good.

 

[Miwa]

This is an interesting post since I had the exact opposite scenario. We had several inches of snow dumped atop ice, I’m on the downslope on the road, my car is holding fine while cars around me are sliding and can’t make it up the hill. Oh I slid when I came to a stop. But once held it was rock solid (and I did have to put it in park to go help a stuck BMW). I walked away impressed as hell with the car’s handling in snow/ice...quite the opposite of it rolling when it should be stopped. Yes it slides on ice but it’s better than any car I’ve had before, and it definitely has never rolled while in park.

You'd be a lot less impressed if you had summer tires on during winter in Minnesota.

 

[Vim Schrotnock]

I did consider the summer tyres issue. It does not explain these incidents.

This does sound crazy, and I'd like to add a bit to your consideration of driving on summer tires in the winter. In racing you learn the absolute most important part of your car and the one you want to pay more attention to than any other component is the tires. Wrong or worn tires, wrong pressure, cold tires, loose lug nuts - anything wrong with your tires and it doesn't matter whatever else is going on with your car - you're screwed. They are the only thing that connects you and your car to the road. I've personally witnessed an accident - a full 720 - of a Porsche on summer tires in the snow on the highway. It was an AWD Turbo 911 and the owner probably thought they were fine since it was AWD, which I suspect is a pretty common mistake. He passed us on the highway in a snowstorm and I said to my wife - he doesn't realize he's going to spin out. Sure enough, he hadn't gotten 200 yards ahead of us when he did just that - right in front of the cop cars that were attending to another car that had gone off in a ditch. Driving on summer tires in the winter is not a good thing, and as others have said - the compound gets hard as a rock and it can be like driving on ice - even in perfectly dry conditions. Driving in snow with these very wide tires that have a very narrow front/back contact patch is just asking for trouble.

 

[PanameraFrank]

Just to reiterate because it is very much a matter of life and death. If you drive on Summer tires in freezing conditions it's just a matter of time until you crash. Summer tires are no longer grippy at freezing temperatures and there's nothing any car, brakes, or computer can do to overcome bad tires. You're basically driving around with 4 sleds under your car at that point.

 

[Jancha]

I did consider the summer tyres issue. It does not explain these incidents.

It certainly could. Summer tyres on snow are completely hopeless.

 

[jetbox]

Now I’m worried, my car is currently outside my house on a slope in the snow....

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