Off The Line

I was messing around on some country roads this weekend - having the kind of fun I typically can't on my daily commute - and I spent a little time with the paddle shifters. I'm the first to admit that taking control of the shifting isn't within my comfort zone as I've always had automatic cars. Nevertheless, I took advantage of the lack of traffic and open roads to get a little practice doing more than just shifting to make the engine growl a little louder - until the EfficientDynamics stepped in and killed my fun by putting it back in auto mode.

Getting to my point, has anyone taken the time to test the car's launching abilities? While I find that the car shoots off in auto mode by stomping the throttle past resistance point (even without being in Sport+/DTC active), I did a few launches using the paddles, and it seemed faster than auto mode. I didn't have the ability to do any fancy timed runs, but it just felt more exciting. Maybe the excitement of "pulling the trigger" up shifting and being more involved in the process gave me an inflated sense of thrust, not sure. Just curious if anyone has played with the car and has some objective information on straight line acceleration.

I'm hoping to get a chance to play with launch control on the M5/M6 when I'm at the PC next month, but I'm still curious about my 650xi.

Just curious what y'all have experienced. I've heard that some cars launch better by stomping the pedal while others perform better when manually shifting. This is all pretty new to me, so I'm curious to hear what y'all have to say.

I'm well-versed in paddle shifting. I'll try it this week.

Looking forward to seeing what you think.

I was playing with the Sport+ mode which engages "Dynamic Traction Control". I am not sure if X-Drive also has DTC, but on my non-X-Drive, activating DTC is the fastest way off the line. It allows for enough wheel spin to get you moving fast, without DSC intervention. Of course with my winter tires on, I have to modulate the power carefully. I can easily spin them off the rims.

Using Sport+ provides the fastest transmission shifts irrespective of paddle use. If you keep it floored, the computer knows the optimum shift point. Using the paddles doesn't make it faster - just more fun.

It should actually de-activate it. The light pops up to let you know it is off, not on. Hold the DTC button down for a bit and it will turn off completely. You should be able to spin the tires in this mode if you like.

Sorry Petriej. You are incorrect. I think you are confusing DSC with DTC. Putting the car in Sport+ or pushing the DSC button briefly ACTIVATES DTC, leaving DSC on. Holding the button for 5 seconds or so DEACTIVATES DSC. You know DTC is active when the word "TRACTION" illuminates in the tach.

I see. Thanks for the clarification.

I have a 550xi with Dinan tuning and my dragstrip results are linked below. In prinicple, the launch results should be similiar for the 650xi, but I won't be able to confirm until this Spring.

First Time - Dragstrip

12.6s@112mph by Mrs Dunderhi

Originally Posted by Bönz

Sorry Petriej. You are incorrect. I think you are confusing DSC with DTC. Putting the car in Sport+ or pushing the DSC button briefly ACTIVATES DTC, leaving DSC on. Holding the button for 5 seconds or so DEACTIVATES DSC. You know DTC is active when the word "TRACTION" illuminates in the tach.

The DTC and DSC thing is a but confusing, but, as usual, Bönz has it right. I didn't understand the systems until I went to the PC and the driving instructors walked us through it - they were much better than the people who wrote the manual.

xDrive does have DTC which is activated when Sport+ is selected. DSC can also be turned off completely, the same way as the RWD version.

Does anyone notice a remarkable difference between Sport and Sport+ aside from DTC active? Do the shifting and throttle change? I don't really use Sport+ very often (don't trust myself enough to lose the nannies lol), so I have limited experience with this. Luckily, in less than a month, I'll have lots of on-the-track experience with these settings, in an M5/M6 no less Can you tell I'm excited? lol

You raise a good question, I've wondered the same myself. I'm only speculating here, but my guess is Sport and Sport+ are mostly the same except that Sport is configurable and Sport+, as you stated, turns on DTC and reduces DSC intervention. Trans, shocks, throttle and steering are probably the same as Sport, again depending how it is configured in iDrive.

Originally Posted by Bönz

You raise a good question, I've wondered the same myself. I'm only speculating here, but my guess is Sport and Sport+ are mostly the same except that Sport is configurable and Sport+, as you stated, turns on DTC and reduces DSC intervention. Trans, shocks, throttle and steering are probably the same as Sport, again depending how it is configured in iDrive.

That's why I tend to stay away from Sport+... All the noise and acceleration while knowing that the computer is watching over me to step in and counteract my humanity/stupidity

If I have x-drive and want to spin my tires and burn some rubber what settings should I use ? The traction is amazing but it would be nice once in a while to be able to spin them. I was surprised to hear that winter tires would spin more than summer tires, is that true ?

Originally Posted by McBucky

If I have x-drive and want to spin my tires and burn some rubber what settings should I use ? The traction is amazing but it would be nice once in a while to be able to spin them. I was surprised to hear that winter tires would spin more than summer tires, is that true ?

I don't have personal experience with my recently ordered 6er yet, but I do have experience at the dragstrip with my Dinan tuned F10 550xi. The best you will be able to do is a chirp with traction control off and engine braking. Of course you can cheat and oil the road, but all you would accomplish by spinning your tires is taking 100s to 1000s of miles off of your tire's lifespan. As far as snow tires are concerned it depends on the type you have. If you have studless snow tires that have terrible dry traction, then you might have a shot spinning them, but you'll destroy there usefulness much earlier than necessary. If you have performance Winter tires, then from my personal experience - again at the dragstrip - they won't spin just like Summer tires.

I can spin the crap out of both my summer and winter tires if I turn on DTC. It sounds counter-intuitive, but when activated, DTC allows for tire spin in snowy conditions, as well as dry. I do not have X-drive.

Generally speaking, even performance winter tires do not have the rotational grip of summer tires, at their appropriate respective operating temperature. Summer tires are softer with larger tread blocks and generally stick better in all directions. In normal driving, with all the nannies working, my DSC light flashes far more often with the winters than it does with the summer tires. This implies that they are about to spin. Same was true with my M3. Again, I am talking about RWD cars here.

There is no doubt that burning rubber lowers the life expectancy of your tires. Not a bad thing if you want to chew through your RFTs and get some good Michelins on there sooner.

Originally Posted by Bönz

I can spin the crap out of both my summer and winter tires if I turn on DTC. It sounds counter-intuitive, but when activated, DTC allows for tire spin in snowy conditions, as well as dry. I do not have X-drive.

Generally speaking, even performance winter tires do not have the rotational grip of summer tires, at their appropriate respective operating temperature. Summer tires are softer with larger tread blocks and generally stick better in all directions. In normal driving, with all the nannies working, my DSC light flashes far more often with the winters than it does with the summer tires. This implies that they are about to spin. Same was true with my M3. Again, I am talking about RWD cars here.

There is no doubt that burning rubber lowers the life expectancy of your tires. Not a bad thing if you want to chew through your RFTs and get some good Michelins on there sooner.

Are you running the same width Winter tires as your Summer tires? The Winter tires on my RWD 335d are narrower and spin much more easily. The Winter tires on the 550xi were the same width and never spun period and that's with 511hp.

No, I am running 245 winters and 275 summers, but that is only part of the reason they spin more easily. Remember, at a given tire pressure, tire width only changes the shape of the contact patch, not the total area of contact. It is primarily tread design and rubber compound that distinguish winter tires. Like I said, I can also spin my summers all day long. I think it's your x-drive (which effectively doubles your off-the-line traction) that makes it difficult to get any wheel spin.

Although you did say that all you got was a chirp. This sounds like the computers were still engaged. Are you sure you had DSC off and DTC on? It seems that even with X-drive, a Dinan tune would allow for more than a chirp. But perhaps not.

When I had my E92 M3, I ran 265 rears for both summer and winter. The winter tires were easier to spin. Bottom line, winter tires (even performance winter tires) sacrifice dry traction for snow grip. That is the point.

Originally Posted by Bönz

No, I am running 245 winters and 275 summers, but that is only part of the reason they spin more easily. Remember, at a given tire pressure, tire width only changes the shape of the contact patch, not the total area of contact. It is primarily tread design and rubber compound that distinguish winter tires. Like I said, I can also spin my summers all day long. I think it's your x-drive (which effectively doubles your off-the-line traction) that makes it difficult to get any wheel spin.

Although you did say that all you got was a chirp. This sounds like the computers were still engaged. Are you sure you had DSC off and DTC on? It seems that even with X-drive, a Dinan tune would allow for more than a chirp. But perhaps not.

When I had my E92 M3, I ran 265 rears for both summer and winter. The winter tires were easier to spin. Bottom line, winter tires (even performance winter tires) sacrifice dry traction for snow grip. That is the point.

Certainly, Winter tire have less dry grip than Summer tires, but xDrive provides sufficient grip, even with the traction control completely disabled. xDrive's grip is the reason why my 4760lb car was able to do 0-60 in under four seconds and put down a couple of dozen 12.5-12.6s quarter mile runs at the track - easily beating the E60 M5.