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Phantom braking getting some unwanted attention (at last!)

Irata

Active Member
Oct 16, 2020
1,059
668
UK
I'm unsure about the direct share price link...

However, it certainly needs more attention.

I now get to watch this happen to M3 owners ahead of me on the motorway daily, I just know when they are coming up to the side of that lorry I'll see their brake lights come on.

It's unfortunate when it is the first time they have experienced this as I see the car slow down and drop back. The more experienced drivers are, of course, holding the throttle.

I find it rather embarrassing for Tesla, I don't see other cars doing it. I'm sure other cars do have the same issues, but I don't see it daily.
 
Isn't this linked to switching to vision only in the US. I'd be worried if my car didn't even have radar. Until Tesla give up on trying to do everything with vision it's not going to get fixed. This problem essentially doesn't exist with the TACC on my 2015 Golf that is only using radar. It's like with the auto-wipers, build off of what already works.
 
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Irata

Active Member
Oct 16, 2020
1,059
668
UK
This absolutely does also affect radar cars from Tesla, it's been a phenomenon right from the very start (look at the historic posts) - long before vision only.

I am increasingly thinking Tesla don't exactly source the most quality components out there, their component failure rates and issues (for everything really) are way too high for the industry. They appear to think software can work around everything.
 

GRiLLA

Active Member
Jul 5, 2020
1,936
2,100
UK
I swear there must be something related to calibration in different cars that causes this, as it's such a rare occurrence for me I loose track of the last time I experienced it. Anyway as I'll be trading for a new car in March I guess I'll see if my experience translates to a different vehicle.
 

Irata

Active Member
Oct 16, 2020
1,059
668
UK
I swear there must be something related to calibration in different cars that causes this, as it's such a rare occurrence for me I loose track of the last time I experienced it. Anyway as I'll be trading for a new car in March I guess I'll see if my experience translates to a different vehicle.

No phantom braking, I'd open a service request. 😀
 
I swear there must be something related to calibration in different cars that causes this, as it's such a rare occurrence for me I loose track of the last time I experienced it. Anyway as I'll be trading for a new car in March I guess I'll see if my experience translates to a different vehicle.
Yeah to be honest I feel the same. I've done almost 4,000 miles I think now (not a huge amount I know) but I've only ever had 2 "phantom breaks".

1 of these was when using TACC on city streets which from my understand Tesla has acknowledged it works best on highways. However Autopilot on highways it works fine, I had 1 phantom break which was due to a bridge and it only slowed down a little, it feels horrible and sharp but only took off maybe 5 mph.
 

GRiLLA

Active Member
Jul 5, 2020
1,936
2,100
UK
I agree.

Do we know if the forward collision warning setting alters sensitivity? That could explain some of the different experiences.
I don't know, but no one ever really seems to want to investigate why there are differences between different people's experiences, happy to just moan.

For Reference I have

Forward Collision Warning : Medium
Lane Departure Avoidance: Assist
Emergency Lane Departure Avoidance: On
Automatic Emergency Breaking: On
Obstacle-Aware Acceleration: on
Traffic-Aware Cruise Control Chime: On
Green Traffic Light Chime: On

Set Speed: Speed Limit
Offset: percentage +4%

Follow Distance: typically 6, unless the road is very busy when 4.
 
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Bouba

Active Member
Sep 23, 2021
1,257
1,124
France
I don't know, but no one ever really seems to want to investigate why there are differences between different people's experiences, happy to just moan.

For Reference I have

Forward Collision Warning : Medium
Lane Departure Avoidance: Assist
Emergency Lane Departure Avoidance: On
Automatic Emergency Breaking: On
Obstacle-Aware Acceleration: on
Traffic-Aware Cruise Control Chime: On
Green Traffic Light Chime: On

Set Speed: Speed Limit
Offset: percentage +4%

Follow Distance: typically 6, unless the road is very busy when 4.

This is the first time I’ve come across the theory that phantom braking could be related to settings. But this would surely be the easiest fix in the world for Tesla....
 

GeorgeSymonds

Active Member
Moderator
Mar 16, 2018
2,311
2,456
UK
I've had 3 cars with this type of cruise control, 2 Teslas and a BMW, and I've done a lot of miles in all of them (20k+ miles in each).

The BMW has never phantom braked.
The first Tesla with Mobileye/AP1 has never phantom braked.
The second tesla with Teslas hardware and latest software phantom brakes, albeit not very often.

I'm sure it has happened and can happen to any car, but in my personal experience the odds do point to an issue with the Tesla home brew implementation. It's possible its trying to be too clever to be honest, looking for ghosts that aren't there like shadows under bridges and lorrys out to get you. The other systems may well be simple in comparison, and at the limit of what they can do, but they work.

Another hunch is Tesla got a lot worse after the Joshua Brown decapitation as the car didn't see the lorry and while it was a 100% misuse of the system, it's still bad press for Tesla. All AI models require a balancing of false negatives and false positives - reduce the chances of a false negative (there is an obstruction but you don't see it) will result in an increase in false positives (there is no obstruction but you think there is). The hunch is tesla moved the dial to reduce false negatives but in doing so increased false positives ie phantom braking.

The other aspect of this is time of year and weather can play a massive part. It's fairly logical that the system is responding to what it sees and shadows, contrast, lens flare, brightness etc which all vary significantly over the year will result in different responses. Plus, if the speed is being set by the vehicle in front rather than an open road in front it could result in very different outcomes (the car is looking at other clues to how fast it can go). Maybe the settings make a difference too for some reason, a different set of rules in the car.

The point I guess is you can drive the same bit of road and get different results depending on a bunch of external factors, drive in traffic might be better (or worse) than driving on an open road, driving at 7AM might be different to 10AM as the sun is higher in the sky etc.
 
About time too! I'm on the M1 every day for 40 miles total on my commute and have on average 2-3 phantom braking episodes a week. About time this got some serious press and hopefully resolved. It is my per hate about my M3.

And 'cover the accelarator' suggestions every time I overtake a lorry on the M1... I might as well not even use autopilot as there are so many trucks and average speed cameras.
 
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MrT3

Active Member
Jun 26, 2021
1,671
1,106
UK
About time too! I'm on the M1 every day for 40 miles total on my commute and have on average 2-3 phantom braking episodes a week. About time this got some serious press and hopefully resolved. It is my per hate about my M3.

And 'cover the accelarator' suggestions every time I overtake a lorry on the M1... I might as well not even use autopilot as there are so many trucks and average speed cameras.
What is your Forward Collision Warning setting?
 
Another one for never having experienced phantom braking with other manufacturers.

I had a few Jags with what they call Adaptive Cruise Control that never gave me any trouble at all and at one point I wasn't doing 1,000 miles a week using it regularly.

One thing I did like, now that I look back, is that you could engage it as regular cruise without the adaptive part - I think the Tesla system could do with a similar option.
 

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