Why is AP dropping 20mph on freeway

[Beans4Me]

About a month into ownership here. On the last few trips with AP; going home during rush hour in the HOV lane with a wall of cars to the right while cruising at 75mph the car will randomly drop into the 50s. I can’t figure out why but it brakes pretty hard. I’m sure the pile of cars behind me are getting pissed. Yesterday I just used cruise control and skipped AP because I wanted to this phantom braking.

It’s not a speed limit issue because AP does fine on this road during normal hours. Is AP being cautious because of the wall of cars? Is there a setting to reduce this tendency?

 

[Konicom04]

I do believe it is a thing, where the computer will "adjust" the speed if it senses you're blowing by traffic,

 

[EVRider-FL]

Yes, it’s a feature, and it should be documented in the manual under Autosteer. I would include a reference but I can’t access the online manual when using my VPN.

 

[Twiglett]

The manual shows the times this will occur and what this display looks like

 

[Jane4]

About a month into ownership here. On the last few trips with AP; going home during rush hour in the HOV lane with a wall of cars to the right while cruising at 75mph the car will randomly drop into the 50s. I can’t figure out why but it brakes pretty hard. I’m sure the pile of cars behind me are getting pissed. Yesterday I just used cruise control and skipped AP because I wanted to this phantom braking.

It’s not a speed limit issue because AP does fine on this road during normal hours. Is AP being cautious because of the wall of cars? Is there a setting to reduce this tenden

I am experiencing something similar with my 2020 Model 3, LR, on Cruise Control. I would call it aggressive slowing however--it's not like the braking I have experienced in the past. And the car doesn't seem to want to respond to my attempts at speeding up. I'm calling the service center tomorrow. It feels very unsafe. The braking was just annoying. This feels more dangerous.

 

[JulienW]

Here is an example of why it was implemented when a car pulls into the HOV lave from a stoped lane and you have emergency braking event. From almost 3 years ago before AP/FSB Beta started slowing down for adjacent lanes going slow.

 

[Jane4]

Here is an example of why it was implemented when a car pulls into the HOV lave from a stoped lane and you have emergency braking event. From almost 3 years ago before AP/FSB Beta started slowing down for adjacent lanes going slow.

The times the aggressive slowing has occurred, there were NO other cars around. I just made an appointment withe Service Center--a week away.
This is something totally different from anything I have experienced in driving our 2020 Model 3.

 

[Jane4]

Yes, it’s a feature, and it should be documented in the manual under Autosteer. I would include a reference but I can’t access the online manual when using my VPN.

Is auto Steer the same as Cruise Control? because that is all I use. This is not the same as the Phantom Braking.

 

[EVRider-FL]

Is auto Steer the same as Cruise Control? because that is all I use. This is not the same as the Phantom Braking

No, Autosteer is TACC (cruise control) plus lane keeping. The feature I referred to earlier shouldn’t apply when just using TACC.

TACC will slow down if you approach an exit and you’re in the lane closest to the exit, because it assumes you might take the exit. If you pass exits from the HOV lane, perhaps that’s why you’re slowing down.

 

[JB47394]

Is auto Steer the same as Cruise Control? because that is all I use. This is not the same as the Phantom Braking.

From the Tesla support page on Autopilot, Enhanced Autopilot, and Full Self-Driving Capability:

Autopilot​

Autopilot includes the following functionality and features:

• Traffic-Aware Cruise Control: Matches the speed of your car to that of the surrounding traffic
• Autosteer: Assists in steering within a clearly marked lane, and uses traffic-aware cruise control

So Autosteer is lane keeping, and Traffic-Aware Cruise Control (TACC) is cruise control. The "traffic-aware" bit is that it won't slam into the car in front of you.

 

[Jane4]

thanks