[rs1987]

Since this is my first BMW, I'm not at all familiar with the various nomenclature and technical details of the drives modes, so I'd really appreciate it if someone could give me a quick primer so that I know precisely what the car is likely to do in any given situation.

The way I understand it is that MDM is basically DSC with much more permissive limits, right?

If so, in practical use, how loose are the limits when MDM is set?

For example, would using MDM mode while doing some canyon carving be a bad idea?

Then, understanding the dynamics of DSC would also be helpful. Will DSC allow the rear to step out a bit, or not at all?

Finally, what's the actual difference between 4WD and 4WD Sport modes given that the differences between DSC and MDM seems to encapsulate the difference between the two 4WD modes. I'm struggling to appreciate the difference between the two, unless 4WD Sport just increases the rear bias a bit...?

[Simon H]

The way i understand it is, that in 4wd sport, it sends more power to the rear wheels before DSC intervenes, allowing a more tail out attitude, and i wouldnt recommend this in anything but dry conditions, personally. Ive had my M5 Comp let go unintentionally in the wet, when on it. MDM is really the same as 4 wd sport, i think, in that it lets you have more slip at the rear before before it cuts the power slightly. It does get a bit headscratching , in understanding it all. Dont forget, M X Drive, is rear wheel biased, and it then sends power to the front axles when it senses slip. Someone else may give a better literate explanation than i, but i know in my own head what i mean.

[pcai]

1. Yes, MDM allows more slip angle. It actually allows quite a significant amount of slip angle-I think I once countersteered full opposite 180 degrees on the steering wheel and it felt like MDM still didn't kick in. So yes, MDM definitely lets you get the tail out.
2. I would still drive in MDM for mountain passes. On a dry and nice day for driving, you really have to intentionally provoke the car in MDM for the tail to step out. It's basically you get what you ask for in this scenario. It's not similar to driving this car on summers in the cold and wet-that's the only time I feel like the car can unintentionally step out.
3. When I start pushing the car, I never drive in DSC on, but I also know that the car feels sketchy in the wet and cold on summers with DSC on.
4. The 4WD system in the F90 is always variable regardless of what setting you're in. On the highway and etc., it will automatically become 2WD, and whether you're in 4WD or 4WD sport, the power distribution is always changing. 4WD sport is just more rear-biased. MDM only works in 4wd sport, while you can only choose DSC fully on or off in 4WD.
5. In summary-there's a reason why BMW made MDM only available in 4WD sport. It's the sweet spot sporty driving setup in this car. With adequate temps and a dry surface, this car really won't bite you in MDM. Even in 2WD on a nice day, you stomp on it from 1st and the car hooks up relatively cleanly. There's a bit of wheelspin but nothing too crazy. Sure is fun. Give it a try sometime.

[Aronis]

Rear wheel 2WD drive mode is dangerous. Period. The fact that BMW didn't give a mode of rear wheel only WITH traction control on is just dumb. The rear wheel drive mode (2WD) is without any nannies accept for limited slip differential and is dangerous. On a wide open parking lot with no obstacles when you are filming a BMW commercial it can look 'cool' much like an SUV being filmed sloshing through the snow on a mountain pass. It's just BS. Prior M5 with rear wheel drive had traction control. my 2 cents worth.

Mike

[rs1987]

Originally Posted by Aronis

The fact that BMW didn't give a mode of rear wheel only WITH traction control on is just dumb.

Agreed. My RWD C63 has traction control, so no technical reason I think of except lack of will on BMW's part to do so

Thanks to the other commenters.

I think I get the MDM mode: don't use in the wet (I would not have anyway), but ok for canyon carving on good, dry tarmac. But be ready to catch the rear because it can and will slip if provoked enough although it's controllable if you're expecting it. Does that about sum it up?

So what about DSC? Will it simply not slip at all?

[Aronis]

I usually drive in MDM 4WD, sport plus, etc....unless chilling.....or in snow.

Mike

[Simon H]

Originally Posted by rs1987

Agreed. My RWD C63 has traction control, so no technical reason I think of except lack of will on BMW's part to do so

Thanks to the other commenters.

I think I get the MDM mode: don't use in the wet (I would not have anyway), but ok for canyon carving on good, dry tarmac. But be ready to catch the rear because it can and will slip if provoked enough although it's controllable if you're expecting it. Does that about sum it up?

So what about DSC? Will it simply not slip at all?

I think you are getting yourself mixed up a little, and its not surprising really, it is a little confusing. The DSC is really all the functions we are mentioning here, within the cars settings. Have a look at this video, from around 4.20 secs, and see if it can make things clearer for you ?.

[adeuel]

Originally Posted by Aronis

Rear wheel 2WD drive mode is dangerous. Period. The fact that BMW didn't give a mode of rear wheel only WITH traction control on is just dumb. The rear wheel drive mode (2WD) is without any nannies accept for limited slip differential and is dangerous. On a wide open parking lot with no obstacles when you are filming a BMW commercial it can look 'cool' much like an SUV being filmed sloshing through the snow on a mountain pass. It's just BS. Prior M5 with rear wheel drive had traction control. my 2 cents worth.

Mike

A couple years ago, I drove a few miles after a car wash and was in 2wd at a stop light. Left turn, slight incline, off camber from the light. Went to take off from the light, and did a 540 in the median that was sprinkled with road dust. Didn’t expect that at all. Luckily no other traffic coming. Semi-wet tires after car wash and road dust obviously a contributing factor, but I agree, 2wd definitely is jumpy at times.

[Resjudicata]

think of it as track mode vs street mode. it will let you get out and attack the track with less of the electronic nannies.

we don't have cannon out here, but we do have mountains and hills. I'd suggest keeping it in DSC, not MDM if you're not going to track.

if you find it too restricted after 1-2 weeks; then go sport MDM. give it some time.

[Spunky]

Originally Posted by Aronis

Rear wheel 2WD drive mode is dangerous. Period. The fact that BMW didn't give a mode of rear wheel only WITH traction control on is just dumb. The rear wheel drive mode (2WD) is without any nannies accept for limited slip differential and is dangerous. On a wide open parking lot with no obstacles when you are filming a BMW commercial it can look 'cool' much like an SUV being filmed sloshing through the snow on a mountain pass. It's just BS. Prior M5 with rear wheel drive had traction control. my 2 cents worth.

Mike

Obviously, YMMV depending on skill level/experience and I don't recommend anyone go out of their comfort zone, but the M5 is actually pretty amazing in 2WD and it feels it's been deliberately made to be driven like that, not just a drift mode/gimmick that journalists would let you believe. If you don't push it too far and have the modes set in a reasonable way(Sport throttle, Comfort steering/suspension and gearbox in the middle), it feels great, has tons of mechanical grip and although DSC is off, the rear diff keeps it straight, which is amazing for that power level. Yeah, the diff could be twitchy at the limits and there is a delay that might take you off guard when you try to slide it and this only confirms that the mode is not meant for drifting and it's not progressive at all. With some experience you can learn how to trick the diff and keep nice long drifts, but it's still a silly thing to do

The main reason I keep it in 2WD for most of my drives is how the steering feels more natural and you don't get that pull that you can feel even in 4WD Sport.

I also only drive like that in the dry(99% of SoCal weather) or when it gets wet, I can get into some silly stuff and save some rubber

[Aronis]

Originally Posted by Spunky

Obviously, YMMV depending on skill level/experience and I don't recommend anyone go out of their comfort zone, but the M5 is actually pretty amazing in 2WD and it feels it's been deliberately made to be driven like that, not just a drift mode/gimmick that journalists would let you believe. If you don't push it too far and have the modes set in a reasonable way(Sport throttle, Comfort steering/suspension and gearbox in the middle), it feels great, has tons of mechanical grip and although DSC is off, the rear diff keeps it straight, which is amazing for that power level. Yeah, the diff could be twitchy at the limits and there is a delay that might take you off guard when you try to slide it and this only confirms that the mode is not meant for drifting and it's not progressive at all. With some experience you can learn how to trick the diff and keep nice long drifts, but it's still a silly thing to do

The main reason I keep it in 2WD for most of my drives is how the steering feels more natural and you don't get that pull that you can feel even in 4WD Sport.

I also only drive like that in the dry(99% of SoCal weather) or when it gets wet, I can get into some silly stuff and save some rubber

I hear you, but that time you hit something wet you will be surprised. The older rear wheel drive cars of yore did not have this kind of power, so it was easier to keep it on the road relatively speaking. I think you would have that feel you want with the safety of traction control if BMW had simply designed it that way. Totally no traction control is just asking for trouble.

Mike

[Fantastic 5]

I'll never understand the point of having 2WD with no traction control. It's not a Dodge Viper.

[Spunky]

Originally Posted by Aronis

I hear you, but that time you hit something wet you will be surprised.

As I said, everyone's case is different. I try to spend some time in getting to know a car and its limits first and in all cases, I stay rational. This allows me to drive confidently all of my cars with TC off(RWD in the dry, AWD in all conditions) and minimize a potential surprise. Compared to other RWD cars with similar and higher power levels, no matter TC on or off, the M5 is extremely planted and when you learn how not to surprise the rear diff, it's more difficult for it to surprise you.

Originally Posted by Fantastic 5

I'll never understand the point of having 2WD with no traction control. It's not a Dodge Viper.

In this case, you have plenty of TC modes to choose from. Yeah, adding TC to the 2WD mode would have been great for more people to enjoy it like that and I guess there is are legal/safety concerns and they don't want you to drive that way all the time. That's fine.

Still, being able to drive it confidently in that mode, which changes the dynamics of the car in a very noticeable and enjoyable way, is an amazing and unique achievement and makes me like the car even more. Just respect the power, drive it like an M2 that you know can bite, not like the 4WD spaceship that it is, and you get a bonus car with a double tap of a button

[Fantastic 5]

Well, I think there is more liability having it in the car with no traction control. Also, that is the point: I want to drive it like an M2 but the M2 has traction control.