[canuckbmw]

I have a 2017 X3 3.0 and since I am very new to these cars I am not educated as much as others on how the DSC and DTC and X drive all work together. This is my first winter in a BMW as well. Anyway, I have brand new winter tires (bridgestone Blizzak) and so far they have worked pretty well on all conditions. A few days ago I was driving the car up a fairly steep hill ( 20% Plus) with no shoulder , two way one lane each way. I had the car in sport mode and saw I was doing 67Kms going up the hill. Towards the crest of the hill a large gravel truck came over towards me and he didn't see me coming up and he was in the middle of the road coming down. He forced me a bit off the road towards what should be the shoulder but it was filled with a lot of slushy snow and icy patches. Before I could think to do anything ( brake gas etc), the car was quickly sucked deeper into the steep side bank and my first thought was, I am going to ditch into the bank. Instead the car suddenly powered forward, and shot me back out into the road causing the back end to fish out sideways and was wagging me back and forth out of my control into the oncoming lane. As bad luck would have it, another car was right behind the gravel truck and for a split second I was spinning out of control directly into his path. I was so shocked I froze up expecting to hit him and again, the car suddenly shot forward the other way, self correcting the spin and powered me up the hill in complete straight line and back in my own lane. I was incredulous that I didn't hit the ditch or the truck or the car and that I somehow made it safely up this hill. My question is, what did the car do and how did this happen? Should I be turning off any of the traction controls when climbing these snowy hills in future or should I leave them all alone as it appears they just saved me from a bad accident or ditch?all I can remember is that I had my foot on the gas in a steady state meaning I didn't hit the gas any harder nor did I tough the brakes. Any comments or suggestions or others experiences are welcome. At this point I am just going to leave the controls alone so if anyone has any other suggestions or experiences please send them my way.

[G01Mike]

There are many more experienced people on here than me but it sounds to me like it might have been your lane assist making the steering correction to keep you in your lane and the traction control taking over to correct the spin/skid by adjusting the tire speed/brake which is what allowed the car to correct itself into the straight line to continue up the hill. Sounds like everything worked correctly to me. Hopefully others will have more info than me.

[skier219]

80% of what you described is how I'd expect a vehicle to behave on a snowy surface when traveling at the speed you stated (67 kph = 42 mph). Stuff happens fast at that speed when the roads and/or shoulders are snowy or slick. It wouldn't help if one side of the vehicle was on the road and the other on the snow.

The other 20% was probably the vehicle safety systems trying to keep the car going in the direction it though was the intended direction.

I'd suggest finding a wide open snowy parking lot and try to experiment so you know how the vehicle behaves and how the safety systems react.

To be honest, I'd be surprised if driving onto a snowy shoulder at that speed didn't result in some crazy behavior and fishtailing.

[MechX3M40i]

Without knowing exactly what happened, I would say the car safety features did what they were supposed to and kept you safe without colliding with anything or going straight down into the ditch.

I'm guessing it's a combination of DSC (steering you straight after fishtailing, uneven traction between one side on the road and the other side on the slushy shoulder, avoided sliding into the second car) and collision prevention (vs. the gravel truck straight ahead of you) to get you out of trouble.

I would suggest when driving on icy/snowy roads, avoid putting your car in Sport mode and slow down a bit to match the road condition. Throttle response in Sport mode is too high under this condition and increase risk of losing traction.

[canuckbmw]

Originally Posted by MechX3M40i

Without knowing exactly what happened, I would say the car safety features did what they were supposed to and kept you safe without colliding with anything or going straight down into the ditch.

I'm guessing it's a combination of DSC (steering you straight after fishtailing, uneven traction between one side on the road and the other side on the slushy shoulder, avoided sliding into the second car) and collision prevention (vs. the gravel truck straight ahead of you) to get you out of trouble.

I would suggest when driving on icy/snowy roads, avoid putting your car in Sport mode and slow down a bit to match the road condition. Throttle response in Sport mode is too high under this condition and increase risk of losing traction.

Agreed. I now realize sport mode was a bad decision and will keep it in comfort during winter and given the hill climb I was likely going too fast out of fear of not making the grade when the truck came at me. I think its true the car saved the day and I learned a valuable lesson. I count myself lucky!

[SROC3]

Very lucky and very good of the car to "save the day"! I personally think it was a combination of your car transitioning from regular road/gravely to slushy snow. The system overcorrected and thus shot power to the rear wheels and threw you into the other lane, then you being sideways, it repeated this and threw you back into the opposite lane and you likely had the wheel corrected in a straight direction so you just naturally ended up driving straight up the hill.

In an all out snow storm, where the roads are completely not plowed and full of snow, you actually should turn DSC OFF completely so all the power goes to all four wheels. DSC would only keep transferring power to wheels with traction but will eventually get you stuck because the system is not reacting fast enough. There is a youtube video of an X6 going up a steep driveway and doing this.

But anyway, glad you are safe and that nothing happened to you

[MechX3M40i]

For me, I would not turn off DSC and change it to less-sophisticated traction control (short press DSC button) unless I want to do one of these two things only:

1) Launch Control;
2) Car is stationary, getting stuck by snow due to insufficient traction (actually, if this fails too, I might even turn off all traction control temporarily to let wheels freely rotates to 'rock' out of a bad situation if needed, like the good old days).

Having driven in NE for two decades and driven through more than my fair share of blizzards, having a moving car sliding side ways, severely understeer, fishtailing and doing 360 etc. are far more scarier than getting stuck while stationary. I trust that having DSC fully active while the car is moving through slippery conditions is the best way to go.

[Lux700]

Winter tyres are absolutely necessary here in the UK... it was 16°C today!

[sor]

Sounds perhaps like a little fishtail action from the rear bias of the sport mode, followed by correction of fishtail by the AWD nannies.

[titomi]

Originally Posted by Lux700

Winter tyres are absolutely necessary here in the UK... it was 16°C today!

And you call that cold? Summer wheels are fully capable of handling such temperature.