Downhill Braking

[yoozer]

Hope I am not being redundant to another post, but I could not find a good match when searching.

This question applies to driving in Whisper mode (for sure, and not sure about others as they kind of brake anyway) in regular ole Drive (D) - don't bring the (L) gearing into it, as I understand how that works.

My car is a '21 RTE1. In Drive (the gear) I am almost always in Whisper mode for my commute. When I go down a grade (guessing >~10%) the car automatically brakes and maintains whatever speed it engaged at.

Driving a '24 Premium in which I matched all the settings I could (from my terrible memory because I don't have mine around to check against), the car does NOT do this. Am I missing a setting or is inherent downhill braking a feature that was removed at some point? I've gotten really used to it and kinda like it.

Thanks in advance if you know the answer!

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[Kamuelaflyer]

Nothing that could account for this was removed. I would say that 1pd wasn’t engaged if you hadn’t stated you have experience with the MME and set the premium to duplicate your car as best you can recall.

FWIW, I have a 21 Premium AWD and run around in either engage or whisper 90% of the time. I routinely descend some long steep slopes and the car does just fine maintaining the set speed.

 

[yoozer]

Hmm, yeah, see I am wondering if it is some setting I am missing that could make this one drive like mine does. Also, in case anyone else inputs, I forgot to mention that this also totally disregards 1PD and cruise control because the drives I am thinking of I definitely do not have cruise on (it would obvsly maintain speed) and I have never used 1PD. Just drive it old school like it's my '65 lol.

 

[HuntingPudel]

Without CC on and not using 1PD, the car should increase speed if the force of gravity exceeds the aggregate amount of drag on the car (drivetrain friction, motor drag, aero, etc). ??

I have been on a couple of hills with low posted speed limits that caused my car in Unbridled to accelerate past the posted speed limit with my foot completely off of the go pedal. I am unfamiliar with a setting that would prevent this. ?‍?

 

[kltye]

Without CC on and not using 1PD, the car should increase speed if the force of gravity exceeds the aggregate amount of drag on the car (drivetrain friction, motor drag, aero, etc). ??

I have been on a couple of hills with low posted speed limits that caused my car in Unbridled to accelerate past the posted speed limit with my foot completely off of the go pedal. I am unfamiliar with a setting that would prevent this. ?‍?

In Whisper mode, the car maintains the speed by applying mild regen braking while going downhill. I routine drive in Whisper and can see this because I've hacked the IPC to show the power meter and see some regen happening.

 

[AliRafiee]

I have a 22 GT and if I remember correctly it’s like a runaway train going downhill without 1P in whisper.

I 100% drive with 1P Unbridle unless I’m testing something.

EDIT: I was wrong, it maintained the speed it was at the top of the hill. It sped up when I put it in neutral.

 

[HuntingPudel]

In Whisper mode, the car maintains the speed by applying mild regen braking while going downhill. I routine drive in Whisper and can see this because I've hacked the IPC to show the power meter and see some regen happening.

Yep. And sometimes I get increased linear velocity in Unbridled. ??

 

[Mach-Lee]

Hope I am not being redundant to another post, but I could not find a good match when searching.

This question applies to driving in Whisper mode (for sure, and not sure about others as they kind of brake anyway) in regular ole Drive (D) - don't bring the (L) gearing into it, as I understand how that works.

My car is a '21 RTE1. In Drive (the gear) I am almost always in Whisper mode for my commute. When I go down a grade (guessing >~10%) the car automatically brakes and maintains whatever speed it engaged at.

Driving a '24 Premium in which I matched all the settings I could (from my terrible memory because I don't have mine around to check against), the car does NOT do this. Am I missing a setting or is inherent downhill braking a feature that was removed at some point? I've gotten really used to it and kinda like it.

Thanks in advance if you know the answer!

This is normal behavior in 1PD Whisper. If you touch the accelerator pedal while you're moving faster than the cruise control set speed, the car will enter coast mode. Conversely, if you do not touch the pedal while cruise is engaged, the cruse control will allow +1 or +2 MPH over set speed (depending on software version) going down a hill before regenerative braking will kick in and try to maintain that differential over set speed.

If you want to cancel coast mode, disengage and re-engage cruise control. Or just slow down below the set speed. I think changing the set speed will also kick it out of coast mode.

So to summarize, the difference in behavior is likely because you pressed the accelerator pedal with cruise engaged and while traveling above set speed.

The coast feature is nice for passing, with cruise engaged you can just press the pedal to pass someone, then let go and wait for the car to coast back down to set speed. Coasting is more efficient than using regenerative braking in this situation.

Note: All of the above applies to 1PD mode only.

 

[yoozer]

right, but no 1pd or cruise. just regular drive mode. the car still downhill brakes and maintains speed.

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