Unintended acceleration

[McDuff]

I have heard of people thinking the car is accelerating on it's own when they are regenning and then hit a bump which causes the decel of regenning to stop temporarily. Another thing that has happened - because the car does not "creep" in drive, people can forget the car is in drive while they sit in a parking space then they accidently step on the accelerator and drive through a wall at the mall or something,( then blame the car!)

The habit of using the parking brake when stationary is a good one.

 

[robthebold]

The habit of using the parking brake when stationary is a good one.

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]

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...

 

[Dutchi3]

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.

 

[alohart]

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]

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.

 

[Dutchi3]

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.

 

[alohart]

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.

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]

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...

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]

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.

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.)

 

[mojo]

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.

 

[Joff]

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?

 

[Dutchi3]

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.

 

[mojo]

When you activate the cruise control again, the car will accelerate to the set speed by itself.

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.

 

[spawnywhippet]

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...

In 100% of cases where drivers reported this, it was either mistaken pedal application, user error, some kind of interference with external objects (floor mat on the pedal) or misreported behavior. I’m an automotive engineer and have investigated these cases myself. I have never heard of any case anywhere on a modern car where the vehicle had actual unintended acceleration, there are simply too many internal safeguards to prevent this.

 

[ksnax]

In 100% of cases where drivers reported this, it was either mistaken pedal application, user error, some kind of interference with external objects (floor mat on the pedal) or misreported behavior. I’m an automotive engineer and have investigated these cases myself. I have never heard of any case anywhere on a modern car where the vehicle had actual unintended acceleration, there are simply too many internal safeguards to prevent this.

You may find this one an interesting exception to that!

It brings up a very valid concern about 100% drive by wire controls. If the throttle input sticks, and the car won't shut off, options are very limited with no physical disconnect at hand.

 

[mojo]

You may find this one an interesting exception to that!

Except that... it's not an exception. The clip is inconclusive, because it doesn't include any analysis of the cause. Perhaps the throttle really did stick wide open, or perhaps there was something left rolling about on the floor and it jammed the throttle open - we just don't know because it's only part of the complete story.

 

[Mustrum Ridcully]

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...

I noticed with my 21 i3S that last week when I was following with the fancy following speed control ACC another car at about 45 mph he slowed for a rotary [roundabout] we both came down to about 20mph but as he passed out of view behind the harvest decoration in the middle of the intersection my vehicle which was in sport mode hit the juice hard; as I had just in put quite a bit of left rudder. Again not a problem but a surprise nonetheless. I still had the the desired speed set at the highway speed we had been using 65mph this was another lesson that in conditions like this it is best to turn off the ACC.
ANOTHER Lesson learned don't use sport mode at the same time as ACC

 

[ksnax]

Except that... it's not an exception. The clip is inconclusive, because it doesn't include any analysis of the cause. Perhaps the throttle really did stick wide open, or perhaps there was something left rolling about on the floor and it jammed the throttle open - we just don't know because it's only part of the complete story.

If you read/watch more of the full story, the driver was allegedly unable to turn it off or take it out of drive.

Obviously, with the i3, if you touch the brake, the computer steps in to cut off power to the motor, but on every other car I have owned (way too many at this point), the option to take it out of gear has always been there, automatic or manual.

It's impossible to say it wasn't driver error, but this case was pretty extreme. It is possibly a great CYA story for getting caught hauling ***, but my understanding is that the family called the cops for help.