So here is the situation. M3 AWD. Leaving a parking garage in very slow stop and go traffic. On a downward incline of about 5 degrees. With the navigation set to a local supercharger about 15 minutes (10 mile drive away). Stopping mode set to "Hold"
At each time I came to a stop and without using the brake and just letting the car coast to a Hold, the car would lurch back and forth about 4-6 inches several times and then come to a somewhat jerking stop. So here's my theory. It was cold out (about 40 degrees F and the car had been sitting for a while) so the car was attempting to drive in FWD only so as to heat up the battery. Since I was driving slow it only had to use one motor or the other. If that's the case then the front motor (induction motor) isn't nearly as good at stopping the car on a mild down slope as the back motor (permanent magnet). And it struggles to bring it to a smooth stop when that is the only motor engaged.
I should say that I have never seen this behavior before and that as soon as I got to level ground it went away. It also never appeared for the rest of the drive to the supercharger at any of the stops along the way. Nor has it occurred again before or after the incident. Note: I've come to a stop like this many times on a down slope and never had it lurch like that. But all the times before I wasn't navigating to a supercharger.
Does that explanation sound plausible? Or would some other theory all together explain it?
At each time I came to a stop and without using the brake and just letting the car coast to a Hold, the car would lurch back and forth about 4-6 inches several times and then come to a somewhat jerking stop. So here's my theory. It was cold out (about 40 degrees F and the car had been sitting for a while) so the car was attempting to drive in FWD only so as to heat up the battery. Since I was driving slow it only had to use one motor or the other. If that's the case then the front motor (induction motor) isn't nearly as good at stopping the car on a mild down slope as the back motor (permanent magnet). And it struggles to bring it to a smooth stop when that is the only motor engaged.
I should say that I have never seen this behavior before and that as soon as I got to level ground it went away. It also never appeared for the rest of the drive to the supercharger at any of the stops along the way. Nor has it occurred again before or after the incident. Note: I've come to a stop like this many times on a down slope and never had it lurch like that. But all the times before I wasn't navigating to a supercharger.
Does that explanation sound plausible? Or would some other theory all together explain it?
