[saudisinaudis]

We both have xDrive M3s, both have our cars broken in (mine is at 3000km, his is at 33k), and fill from the same gas station. In roll races, either 60km/h or 70km/h, his car walks mine like they’re totally unequal. Similarily, he smokes the Dark Horse regardless of how late he is responding to honks, while if I make the slightest delay and miss the initial bite I will not catch up.

For some reason he prefers rolls on MDM mode, but from what I’ve read at 60km/h and xDrive this shouldn’t make a difference. He has the gear on manual, shifts to lowest and on WOP turns it auto for computer shifts. I hold the left paddle for lowest gear, and then go WOP without worrying about the switch. We both have our M1 set to D3.
Both cars have the same cabin and trunk weight too.

Could it be that his car’s engine has settled in more due to higher mileage, or have I simply lost some of kind of jackpot with these cars?

[Berzerker]

So you're testing in different conditions (MDM vs not) but you simply reading something makes you dismiss it? Why don't you try actually using the same settings for comparing?

I'm not sure what your definition of "smoking" is but if he's actually doing that much better than both yours and other similar cars, then he's not stock.

[FC4]

Swap drivers and race.

[Ximian]

Easiest test would be switching cars and comparing. Perhaps your friend also has some modifications they aren't disclosing. Or your car is cursed after what happened to that kitten.

I wouldn't expect a higher mileage car to have more power as engines often lose power with age.

[pizza240]

Do you have the same wheels and tires?

https://g80.bimmerpost.com/forums/sh...3#post27956883

[saudisinaudis]

Originally Posted by Berzerker

So you're testing in different conditions (MDM vs not) but you simply reading something makes you dismiss it? Why don't you try actually using the same settings for comparing?

I'm not sure what your definition of "smoking" is but if he's actually doing that much better than both yours and other similar cars, then he's not stock.

Yeah, I am very hard-headed when it comes to these things. I had no reason to believe MDM could give an advantage in a roll race for two xDrive cars, as it did not make sense at the time. We argued so I did not want to be proven wrong by switching and eliminating the power difference between us. But I am aware now, I’ll try this next weekend.

[saudisinaudis]

Originally Posted by pizza240

Do you have the same wheels and tires?

https://g80.bimmerpost.com/forums/sh...3#post27956883

825M vs 826M on his. We both have P0s, although his are more aged.

[mirob]

With everything else being equal why not also make the shifting and traction/grip equal to eliminate those factors? That would have made the most sense - whether you think that's the delta or not.

What about the weight of the drivers?

[saudisinaudis]

Originally Posted by mirob

With everything else being equal why not also make the shifting and traction/grip equal to eliminate those factors? That would have made the most sense - whether you think that's the delta or not.

What about the weight of the drivers?

Maybe 10kg, but I don’t expect it to make that big of a difference?

[mirob]

Originally Posted by saudisinaudis

Maybe 10kg, but I don’t expect it to make that big of a difference?

Yeah, that's negligible. I'm with Berzerker on this. Sounds like you guys are pretty competitive (given that you argue about certain aspects of performance) so it's possible he's done something to his car that you don't know about...

[astroricardo]

.

[SwankPeRFection]

Somebody has done the CSL coding on their car… 🤫

And his engine is a little more broken, so if he’s made a habit of driving like a nut for a while, it’s going to be more eager to go. You barely have 1800 miles. Give it at least 5k miles… geez. Lol

[pizza240]

Originally Posted by saudisinaudis

825M vs 826M on his. We both have P0s, although his are more aged.

Any physicists on this forum who can determine performance differences due to 5.4 lbs of additional un-sprung weight in the wheels?

More aged tires might be lighter too. Could also compare tire pressures.

825M
9.5x19 ET20: 11.0 kg / 24.3 lbs
10.5x20 ET20: 12.3 kg / 27.1 lbs

826M
9.5x19 ET20: 10.8 kg / 23.8 lbs
10.5x20 ET20: 11.5 kg / 25.4 lbs

[SwankPeRFection]

Less than one pound up front and less than 2 in the back per corner…. meh… some, but not enough to account for the amount of difference he’s describing. Unless he’s exaggerating in terms of “walking”. His friend has to have a few small things done to the car to make the engine wanna accelerate more eagerly. And if he doesn’t then it’s simply a combination of the slightly lighter rolling resistance (which is definitely a good thing) and just more miles on the engine and drivetrain.

[SwankPeRFection]

Also, something to add in terms of the whole MDM mode thing. Peak acceleration is also achieved the closer you can get to about 10% slip on the tire as opposed to traction control keeping it tighter than that. It’s possible that he’s able to put down a bit more power to accelerate because less torque transfer is being limited. This is easy to find out… match it and use MDM next time and if it’s still bus lengths, then he’s got something done.

[saudisinaudis]

Originally Posted by SwankPeRFection

Also, something to add in terms of the whole MDM mode thing. Peak acceleration is also achieved the closer you can get to about 10% slip on the tire as opposed to traction control keeping it tighter than that. It’s possible that he’s able to put down a bit more power to accelerate because less torque transfer is being limited. This is easy to find out… match it and use MDM next time and if it’s still bus lengths, then he’s got something done.

In length I’d say he walks me by a bus and a half.
I guess MDM is the biggest culprit as I am not sold by the fact that such little weight difference in rims, tire pressure, aged rubber that does not go past 6lbs of unsprung weight gives him that much of an advantage. He is surprised, too, and wants us to both dyno our cars so we can see if something may be off with my car.
But I’ll try again with MDM in mind first. If he had something done to the engine it would show in the dyno.

Hmm.

[TopJimmy]

If you’re using the manual kickdown to lowest gear (paddle long pull) then he’s got you by the RPM. You need to both start in the same gear and RPM, and shift at the same time (first red bar after yellow on the HUD). Do it when you’re both on the phone talking so you can call your shifts out to each other. That should check car-vs-car.

And it’s true some engines make more power than others for the slight differences in the build.

[iqstick]

I think it's the MDM. My car is a Comp RWD which I'm sure MDM makes a bigger difference in but for the first 5,000 miles or so I always drove my car with traction fully on and now I always drive in MDM and the difference is huge.

[TopJimmy]

Originally Posted by iqstick

I think it's the MDM. My car is a Comp RWD which I'm sure MDM makes a bigger difference in but for the first 5,000 miles or so I always drove my car with traction fully on and now I always drive in MDM and the difference is huge.

The DSC On, MDM, or DSC Off only changes how the car intervenes to reduce power where it sees a need for safety. DSC Off has the least intervention, and all you get is traction control as needed.

Your selected power mode of Efficient, Sport or Plus doesn’t change maximum power either. It only changes the speed between when the gas pedal goes down and the throttle value% increases.

[Seanhfx]

Originally Posted by saudisinaudis

We both have xDrive M3s, both have our cars broken in (mine is at 3000km, his is at 33k), and fill from the same gas station. In roll races, either 60km/h or 70km/h, his car walks mine like they’re totally unequal. Similarily, he smokes the Dark Horse regardless of how late he is responding to honks, while if I make the slightest delay and miss the initial bite I will not catch up.

For some reason he prefers rolls on MDM mode, but from what I’ve read at 60km/h and xDrive this shouldn’t make a difference. He has the gear on manual, shifts to lowest and on WOP turns it auto for computer shifts. I hold the left paddle for lowest gear, and then go WOP without worrying about the switch. We both have our M1 set to D3.
Both cars have the same cabin and trunk weight too.

Could it be that his car’s engine has settled in more due to higher mileage, or have I simply lost some of kind of jackpot with these cars?

It's not him or his car, it's you.

[iqstick]

Originally Posted by TopJimmy

The DSC On, MDM, or DSC Off only changes how the car intervenes to reduce power where it sees a need for safety. DSC Off has the least intervention, and all you get is traction control as needed.

Your selected power mode of Efficient, Sport or Plus doesn’t change maximum power either. It only changes the speed between when the gas pedal goes down and the throttle value% increases.

That is correct but especially in RWD it can kick in very conservatively from my experience. A good example is the first to second shift, with DSC fully on there was always a lag in shifting where as in MDM it is a lot quicker. My guess is there is a tiny bit of slip that happens between those gears.

[forcefed]

Maybe he has the m3 cs...