McDuff
Member
The habit of using the parking brake when stationary is a good one.
Unintended acceleration
- Thread starter Rescuelady
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robthebold
Well-known member
- Joined
- May 11, 2019
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Since the i3 takes the parking brake off for you when you hit the "gas" -- as long as your seatbelt is fastened -- it won't help much in this particular case. But it's still a good habit to use the parking brake when parked. (Cue "but sometimes . . .")
BrianM
Member
I have experienced "unintended" or "unintentional" acceleration with my 2017 i3 several times since owning for the last year or so.
This has occurred when coasting and expecting to slow down with regen braking, instead a surge of acceleration requiring hard braking to rectify.
Fortunately it has not happened in a situation where others' or my own vehicle were at risk, but is enough of a problem to e.g. not want my family members to encounter and deal with...
This has occurred when coasting and expecting to slow down with regen braking, instead a surge of acceleration requiring hard braking to rectify.
Fortunately it has not happened in a situation where others' or my own vehicle were at risk, but is enough of a problem to e.g. not want my family members to encounter and deal with...
The loss of regen, invoking a feeling of acceleration also happens when one drives down a mountain road with regen activated and then encounter a sharp bend in the road. It feels like accelerating in the bend and can be scary if you do not expect it. That is the stability control. Once you get used to it, you can even use it to some extent with the right speed, to "glide" through the bend while regenerating.
On pre-LCI i3's, the temporary loss of regen can also occur when driving over a bumpy section of road where one or more of the rear tires loses traction.
In either case, this isn't unintended acceleration but is unintended loss of regenerative braking so that deceleration decreases which can feel like acceleration. I suppose if this occurs down an incline, actual acceleration might occur, but that would be coasting, not powered acceleration.
BrianM
Member
I'm sorry - but this is NOT loss of regeenerative braking - its much more like switching back to cruise control, and the expereince that this creates.
Good one, a possible explanation. But only when the speed is above 20 miles or so, so not in a parking lot.
Having participated in various i3 fora over 10 years, I have never before read of any verified unintended acceleration event, so yours would be a rare occurrence. It might be worth asking your BMW dealer to increase the integration level (a.k.a., update the system software) in case there's a bug that might be causing this behavior. Unfortunately, you'd probably have to pay for this, and it might not solve the problem.
Gonville
Well-known member
Drive in ECOpro. That solves the head tipping vertigo inducing force changes. It is all to do with head tipping without the forewarning of engine noise change. We are conditioned to expect acceleration if our head tips back. Same way a flight simulator causes the feeling of acceleration by tipping us on our backs. If you have passengers with sensitive ear canals they will know this long before you do.
As when the regen is decelerating , head is tipped forwards, as that is suddenly released by the DCS system , typically on a ‘bump’ , then the head unexpectedly tips back inducing an instantaneous feeling of acceleration. As in the flight sim. Whereas in fact speed is constant just no longer d decelerating. Had this for 10 years now. Folks don’t believe their ears , well do, so drive in ECOpro seems to lessen the effect. Try looking at the Speedo when this happens. Hard but doable.
BrianM
Member
No, that still denies my experience.. Try Restoring Cruise Control when you're exiting a dual carriageway with your feet off either pedal. (That's the experience, replicated several times.) And, boy, being glad you had time to react. (And, amazingly, it was a smooth piece of tarmac on the slip road.)
If I experienced that in my car, I would not drive it any further - it would go straight to a BMW garage to be investigated and fixed. There is no way that that should be happening, and - if it really is accelerating of its own accord - it is (IMO) faulty and intrinsically unsafe.
My experience makes me inclined to agree that it is the interruption of regen, but if this is a experience you can reproduce, what is the MPH increase you experience and what is the angle of the hill you are going down? Can this acceleration happen while going uphill?
When you have cruise control set to a certain speed, and temporary disable it to decelerate, the previous speed is still stored. When you activate the cruise control again, the car will accelerate to the set speed by itself. Very handy. But when you activate the cc by accident, it leads to unwanted acceleration. I am shure many have experienced this once or more.
It depends what you mean by "activate". If you mean "turn on the cruise control system", that's not correct. The system should remember your previously set speed only while the system is active - in which case you can return to that speed by hitting the "Resume" (RES) button.
Just turning the cruise control on should not cause the car to accelerate by itself, because turning off the system deletes any saved speed. So: pressing the "RES" button immediately after you have turned on the system should cause no acceleration - it has no previously stored speed to "remember".
And further: note that if a previously set speed is lower than the car's current speed, pressing the "RES" button will cause the car to brake to attain the set speed, if necessary (though on my 2021 car this is quite a gradual process - it won't sudden slam on the brakes).
Of course, the car will accelerate "unexpectedly" if a driver already has the cruise control active and hits the "RES" button when they actually intended to press the "SET" button - but that is user error, and not a fault with the system's design.
