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Phantom Braking vs TACC in Late 2020

Trilodroid

Member
Nov 30, 2020
18
5
USA
On the cusp of getting a new car, and there is so much about the Tesla Model 3 that I love. The one thing I'm worried about is phantom braking during TACC (not talking steering assist, nor FSD). I've been doing a little digging... OK a lot of digging, and it is clear that with each software update something like phantom braking may change dramatically. What I have seen is in July 2020 there was a big update where it was more of an issue. I gather that it has gotten better since then, so I do not want to be worried about issues that are going away or do not apply to me (for instance TelsaBjorn is great on his phantom braking reporting, but I personally don't need to worry about narrow lanes and big trucks on small roads in Norway).

As it is exceptionally hard to get a test drive where I live I need help... can a few posters give me their current take on it per the following... and maybe throw in what sort of town/city/state/country you drive in if you don't mind sharing:

1. TACC and phantom braking on interstate style highways in late 2020.
2. TACC and phantom braking on the way to work. And have you gotten a consistent false positive/phantom brake so you know the one or two spots to watch out for? Does this change with each update?
3. The state of phantom braking over the course of your ownership of a Tesla.
4. Does turning off AEB change anything currently? From February 2020 there is a Youtube video where someone turned off Automatic Emergency Braking and it didn't actually turn that feature off. Guessing that was a temp bug.
5. Would you say staying on the conservative software updates actually avoids major mood swings of AP or is it still hit or miss?
6. Does phantom braking happen more or less if you have more distance or less distance from the car in front of you?

What would be ideal for a buyer like myself is the ability to engage TACC such that it only worries about the car you are following and ignores everything else. That option would be perfect for 90% of my car-assisted driving.
 

Need

Active Member
Nov 22, 2017
2,896
2,206
SoCal
I would say for me, 80% of the phantom breaking has to do with overpass. Is it getting better? I think so, but now I am so used to it that as soon as phantom breaking starts, I will start pressing on the acceleration paddle and cancel TACC (or Autopilot) at the same time. I like to think that my reaction time is fast enough that the car behind me just thought I tapped on the brake lightly.

I know there is 1 spot on the 105 fwy carpool lane going east bound that triggers phantom breaking all the time. There was no overpass and I don't know the reason. But again, I am so trained by it that really I don't think there is any chance of anyone rear ends me because of it.
 
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Losthillsguy

Member
Sep 14, 2019
16
14
San Luis Obispo
I always drive with my foot over the accelerator pedal when in any auto mode in my Model 3. Just today I had a phantom break on a freeway with 2 lanes going in my direction. There were two cars about 200' in front of me moving along. BAM, brakes on! I didn't see any reason for it. It happens still. Never tailgate a Tesla.
 
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SlimJim

Member
Jul 25, 2019
868
660
USA
Phantom braking has vastly improved.
But slowing down near exit ramps still happen so I stay in the left lane.
 

skygraff

Member
May 15, 2018
179
138
Chicago
While I don't do a regular commute in mine, I have been doing a bit more expressway driving (during Chicago's perpetual rush hour) lately and I'm mostly happy with AP & TACC. That said, I don't really think it's made much of an improvement since 2018 and, unfortunately, I haven't noticed any consistency regarding specific points on the road or the sun angle vs overpasses that others have pointed out. Sometimes, at least for wide open roads when I have passengers, I'd love to have the option of dumb cruise control every so often but hoping the new course they're taking with FSD and NN will finally eliminate phantom braking once and for all.

Until then, I'm also in the habit of keeping my foot over the accelerator (opposite of what you'd think would be necessary when letting a computer drive) so I can override phantom braking or the rare occasions where it gets falsely slow speed limit info (easily resolved by scroll wheel or, in cases where it thinks it's on restricted side streets, kicking off AP and just using TACC or manually driving for a bit). I've learned that you can actually rest your foot on the accelerator to avoid stressing the ankle by hovering; if you press too hard, you'll get the warning that cruise control won't be able to brake and, then, just ease back a little.

As for driving in traffic, as much as I'd like to count on AP & TACC, I feel like it's a bit more aggressive with the brake (and, to a lesser degree, acceleration) in stop and go driving but seems to smooth out if you increase the follow spacing. The downside to that, in rush hour, is too much space invites cut offs so, if it starts to bug me, I take control but, thanks to one-pedal driving, it's still less work than the average car.

Every time I drive, I'm reminded how much I really love this car!*


*can't wait for the radio/TuneIn voice commands to come back
 

animorph

Active Member
Apr 1, 2016
2,133
1,529
Scottsdale, AZ
I think if you have HW3 Tesla will eventually fix phantom braking with the new FSD 4D vision. No reason not to make basic Autopilot better, though not with extra features, by sharing the code. HW2.5 won't have the computing power to keep up.
 

Trilodroid

Member
Nov 30, 2020
18
5
USA
@skygraff, thanks for that very insightful feedback. That option to rest your foot on the accelerator pedal, but not too hard (I like the screen feedback "too hard can't brake"), might be the silver bullet for my situation. Super useful.
 

Trilodroid

Member
Nov 30, 2020
18
5
USA
So I have been watching a few beta testers FSD footage on Youtube as of last night, just recently it seems there isn't much if any phantom braking. I have actually seen no phantom braking scanning through videos of 21020.44.15.3 and 21020.44.15.4. FSD has obviously come a long way from just a couple of months ago, so I am hopeful it will fix general AP as well.

I think if you have HW3 Tesla will eventually fix phantom braking with the new FSD 4D vision. No reason not to make basic Autopilot better, though not with extra features, by sharing the code. HW2.5 won't have the computing power to keep up.
 

TLLMRRJ

Active Member
Dec 19, 2019
1,767
1,739
Houston
Well, with my Model 3, because of the phantom braking on the radar cruise control, and often strange behavior of lane keep assist, I consider it not to have any driving aids at all. I even turn off the collision warning because it gives too many strange false alarms. Basically I do all the driving like it's a car from the 60's, pre cruise control. Way to go Tesla!
 
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Trilodroid

Member
Nov 30, 2020
18
5
USA
@TLLMRRJ, well that's definitely a major bummer. I personally expect to not use lane assist super often, and don't mind turning off alerts as I suspect I'd do the same in other cars. But intelligent cruise control is a major stress reliever for me, I have to find a way to make that work at least as well as what I have today.
 

TLLMRRJ

Active Member
Dec 19, 2019
1,767
1,739
Houston
@TLLMRRJ, well that's definitely a major bummer. I personally expect to not use lane assist super often, and don't mind turning off alerts as I suspect I'd do the same in other cars. But intelligent cruise control is a major stress reliever for me, I have to find a way to make that work at least as well as what I have today.

Yeah. Hopefully it works out for you. I do miss having other features like useable rain sensing wipers and useable auto-high beam. Both of those are also flawed beyond use in the Tesla. But hey, I don't have those features in my 1965 Jaguar E-Type either, so at least those cars are on par with each other in terms of tech.
 
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jeffnz

Member
Aug 17, 2019
97
19
New Zealand
I don't have any significant issues with these things. Rain sensor works well for me. Every now and then I need to press the button on the stalk but generally only when it is barely raining.

I use TACC frequently on the highway and it's been fantastic for me, especially when stuck in traffic. In over a year of ownership I've never had any phantom braking due to overpasses or anything really. It's lane following has also improved over that time. Only comment I have now is it tends to turn a bit too late into a curve but this happens mostly when on non-limited access highways with sharper turns. I like the new mode that recently came out where it initially sets the speed to your current speed rather than the speed limit.

When the car was new I had the collision warning set to early and got alarms a few times when rounding a curve where there is a parked car on the side of the street at the apex. Switched it to late warning and haven't had any since. The only other time was what it was intended for which is the car ahead of me stopped short and it gave the alarm before I noticed.
 

arghx7

Member
Aug 6, 2019
489
497
Michigan
just did a 1000 mile road trip and had 1 phantom braking incident at an overpass, and two incidents where another car got a little close/drifted lanes and it hit the brakes more aggressively than a human would have
 

house9

Supporting Member
Nov 16, 2019
354
378
California
For what its worth I just drove from Salinas, CA -> Prescott, AZ (700 miles) and back; almost the entire way using TACC, no phantom braking at all.

However this route is pretty wide open, not many overpasses.
 

Trilodroid

Member
Nov 30, 2020
18
5
USA
Reporting back after I borrowed a 2018 Tesla for extensive testing. So overall, loved it. Wipers were fine enough with auto rain sensing, auto-steer was pretty decent... only tested it a little. But again, my main concern was TACC. Overwall it was more than decent, though not perfect on my roads. Here's what I saw, now granted this is on the old hardware 2.5 I think so not exactly like a new one:

- once or twice a large overhanging tree branch, I think, triggered phantom braking... it slowed maybe 15 mph if I didn't touch the pedal.
- several times phantom braking was triggered in a heavy construction area,... now this is such a messy area I was not surprised at all, and it wasn't unbearable and it didn't slam on the brakes, just moderate braking that I could overcome with a pedal press. However, my old car's ACC doesn't car about side obstacles so it technically is better for this one road.
- I really really love the TACC for stop and go. Being able to let it brake to 0 mph and then auto-resume is huge for me personally. This alone probably is enough for me to deal with any minor phantom braking. Having recently test driven new Audi, BMW, Dodge, and Genesis vehicles, I think Tesla does the slow to zero then auto-resume the best since it can be a very long stop. If I recall, all of the competition I tried had at best a 3 second stop max, and then it required my physical tap on the pedal to resume. And my old car does not do the zero mph stop and go, so this is a feature I really appreciate.

On the topic of AP autosteer... never used lane keeping in other vehicles so this is coming from a very uninformed perspective. I'll say it took some getting used to. This model 3 hugged the center line a little too close for my liking, but it wasn't bad. I do wish you could pull out of the auto-steer with less force, but I think I understand why it is what it is in a Tesla.

Anyway, I'm just about sold. Might be getting a M3 here in the next few weeks. Thanks to all the input here, and maybe this will help someone else out there who is on the fence. And of course... as time goes on, and especially now during the FSD beta, I hope things will improve.
 
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Gasaraki

Active Member
Oct 21, 2019
1,525
1,010
Syracuse, NY
95% of my drives I don't get PB. I noticed that it seems to happen when going up hills (it only slows down) or making right curves with another vehicle on the opposite lane. (All of these happen on two lane roads)

On highways I have very little issues with PB.
 
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WheresMyCar

Member
Oct 29, 2020
22
11
Horsham
I’ve had my M3 LR in the UK for 3 days. Last night on the drive back from work on a 4 lane motorway I was cruising happily at 70 MPH using cruise control with auto steer when very suddenly the car slammed on the anchors really aggressively.

The road ahead of me was clear, there was nothing in either lane to the sides of me and, fortunately, there was nothing behind me in my lane.

This happened travelling anti clockwise on the M25 just after Junction 10. I did notice that there was an overpass which I assume is what triggered the phantom brake.

To be honest it really scared me as I was not expecting it at all. I’m not sure I’ll be using cruise control again which is really disappointing as a major reason for choosing Tesla was the automated driving aids.
 

TLLMRRJ

Active Member
Dec 19, 2019
1,767
1,739
Houston
I’ve had my M3 LR in the UK for 3 days. Last night on the drive back from work on a 4 lane motorway I was cruising happily at 70 MPH using cruise control with auto steer when very suddenly the car slammed on the anchors really aggressively.

The road ahead of me was clear, there was nothing in either lane to the sides of me and, fortunately, there was nothing behind me in my lane.

This happened travelling anti clockwise on the M25 just after Junction 10. I did notice that there was an overpass which I assume is what triggered the phantom brake.

To be honest it really scared me as I was not expecting it at all. I’m not sure I’ll be using cruise control again which is really disappointing as a major reason for choosing Tesla was the automated driving aids.

Welcome to the club. I had the same disappointment.

The AP disclaimer on the screen that says, "this is beta and you are responsible for driving at all times," just doesn't prepare you for the disappointing realization that you will be the driving aid to the car as opposed to the car providing you driving aids.

I have turned off all the driving aids (collision warning, lane departure, AP, auto high beam, auto wipers) because they are all more work than doing it myself.

Some people find it relaxing to watch over the car's driving aids like a hawk waiting for that next random screw up so they can catch it and recover before something bad happens, but I don't.

I still like the cars for what they are, obviously because I have two, but I am not going to lie to myself that any of the aids are a reason to buy a Tesla. For example, I would pay right now in the app for an option to enable basic cruise control so I don't have to do the accelerator on long drives.
 

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