Why does TACC not respond to the distance control setting when AP does?

[thegruf]

Been using TACC more recently due to muck on some roads at this time of the year making AP less reliable.

Curiously I found that changing the setting on the cruise stalk from 1-7 makes no difference to tthe following distance with TACC. The cruise is still working actively as it will vary speed according to the vehicle in front but only at a fixed (and too close for my preference) distance.

I assume everyone else has the same behaviour.
I don't understand why this is.
Can somebody explain the logic to me please.

 

[mblakele]

I haven't noticed that behavior. Yesterday I drove over an hour with TACC alone, and the following distance seemed to be about right: I have mine set to 3, and it maintains about three seconds.

The latest manual I have says that "If a vehicle is detected, Traffic-Aware Cruise Control maintains your chosen following distance, up to the set speed" (2016-10-20 edition, p67): https://www.tesla.com/sites/default/files/model_s_owners_manual_north_america_en_us.pdf

 

[BerTX]

I guess I'm too old to answer this question. My TACC is always set on 7 and would be higher if there was another click or two. I rarely even get the chance to use Auto-steer, as I mostly drive on hilly, two-lane roads. I have re-named it Auto-suicide for the way it veers into oncoming traffic at the top of the hill. Who came up with the "I can't see the lane markers anymore, so I'll steer left" algorithm? I shake my head when people talk about using it with oncoming traffic. Somebody's gonna die.

 

[dhcp]

If you drove the Bay Area commutes with anything than three you would have a constant flood of people cutting in front of you until your car slowed down to a stop. I usually run 3 but sometimes have to go to 2 else the car jerks back on the brakes when another car cuts in front of you.

Auto-suicide, love that.

 

[jdw]

In Montreal, I drive on 1 and people still cut in front of me constantly … especially annoying when there is plenty of room behind me. Every city has a driving personality.

 

[dhcp]

In Montreal, I drive on 1 and people still cut in front of me constantly … especially annoying when there is plenty of room behind me. Every city has a driving personality.

Yikes!!

 

[jdw]

Yikes!!

Yeah ... I'm planning a Dashcam mashup of some of the best moves.

 

[Saghost]

I haven't had occasion to change the distance settings while in TACC but not AP - but I have spent a fair amount of time that way, and the distance has always matched the AP distance for the setting.

The distance is really a TACC feature anyway - and AP is really TACC plus AutoSteer, not some completely separate driving logic.

Are you certain of your observations?

In my experience, it takes the car several seconds to set a new following distance after the lever is moved - especially if the car in front is going slightly faster than you are.

(And yes, drivers on I-95 will angrily move from behind you, pass you on the right and cut in on 2 or 3, and occasionally on 1, during morning and afternoon commutes. People be crazy.)

 

[Moonwick]

I haven't noticed this behavior either. I do notice that OP is in the UK; is it possible that the behavior is different there due to local laws?

 

[RDoc]

In Montreal, I drive on 1 and people still cut in front of me constantly … especially annoying when there is plenty of room behind me. Every city has a driving personality.

Yes, I'd like fractional settings for the same reason.

 

[WannabeOwner]

I assume everyone else has the same behaviour.

I've fiddled with my follow-interval from time to time and concluded that it doesn't seem to make a lot of difference; well ... I expected it to make far more difference. I'll try a more scientific test, timing follow-distance with a stopwatch, next time I'm on a motorway.

 

[ccharleb]

Or you could do a very simple test. Activate TACC at setting 7. Catch up a car and be sure that desire speed is higher than what the car ahead is doing. After a minute or two following the car ahead slower than desire speed, change following distance setting from 7 to 1. Your car should accelerate to get closer to car ahead.

 

[ecarfan]

I have spent a few hours in total driving with TACC earlier this year (not with V8 firmware) and found it to definitely change following distance with setting changes.

Note: the numerical settings are not in units of "seconds" of time between you and the car you are following. This has been extensively discussed in multiple threads in the past on TMC. It is simply a numerical scale. Choose the setting that provides a distance you are comfortable with. I always used 7 on Southern California freeways, I was not comfortable with any lower number. Obviously many people are okay with lower numbers. Not me.

 

[croman]

I believe the settings are a fixed distance called "car lengths" which is 9 feet. Safe following distance is 2 seconds. 2 seconds of following distance varies based on your speed.

 

[MP3Mike]

I believe the settings are a fixed distance called "car lengths" which is 9 feet. Safe following distance is 2 seconds. 2 seconds of following distance varies based on your speed.

@croman Not according to the Tesla manual: "Adjust your following distance
To adjust the distance you want to maintain
between Model S and a vehicle traveling
ahead of you, rotate the cruise control lever to
choose a setting from 1 (the closest following
distance) to 7 (the longest following distance).
Each setting corresponds to a time-based
distance that represents how long it takes for
Model S, from its current location, to reach the
location of the rear bumper of the vehicle
ahead."

So it is a time-based setting, they just don't say what time a 1 vs. a 7 represents.

 

[croman]

@croman Not according to the Tesla manual: "Adjust your following distance
To adjust the distance you want to maintain
between Model S and a vehicle traveling
ahead of you, rotate the cruise control lever to
choose a setting from 1 (the closest following
distance) to 7 (the longest following distance).
Each setting corresponds to a time-based
distance that represents how long it takes for
Model S, from its current location, to reach the
location of the rear bumper of the vehicle
ahead."

So it is a time-based setting, they just don't say what time a 1 vs. a 7 represents.

Interesting. That is NOT what my OA told me nor was it what EM mentioned when TACC was first released but I trust the OM to clearly state it. Thanks!

 

[myskausa]

Curiously I found that changing the setting on the cruise stalk from 1-7 makes no difference to tthe following distance with TACC. The cruise is still working actively as it will vary speed according to the vehicle in front but only at a fixed (and too close for my preference) distance.

Same Problem: My 2017 MS P100D On AP 1-7 makes no difference to the following distance with TACC. Ver.2019.32.12.2

 

[Manitoba Keith]

Same Problem: My 2017 MS P100D On AP 1-7 makes no difference to the following distance with TACC. Ver.2019.32.12.2

Mine works perfectly [Ver.2019.32.12.2] as long as my speed is set slightly higher than the leading vehicle. I also feel more confident using a shorter distance (smaller number) as the computer reacts much faster than I can. Being closer also allows better drafting especially with a semi leading and I don't mind going a bit slower or faster if drafting.

 

[myskausa]

Mine works perfectly [Ver.2019.32.12.2] as long as my speed is set slightly higher than the leading vehicle. I also feel more confident using a shorter distance (smaller number) as the computer reacts much faster than I can. Being closer also allows better drafting especially with a semi leading and I don't mind going a bit slower or faster if drafting.

Set on distance 1. No response to any change 2,3,4 etc. If set on distance example 4 still AP TACC keep distance 1.
Strange.... Got to call SC.

 

[Manitoba Keith]

Set on distance 1. No response to any change 2,3,4 etc. If set on distance example 4 still AP TACC keep distance 1.
Strange.... Got to call SC.

Have you tried it on 7, drive for a while then turned it down to 1 gradually? I think you need to be going faster than 45 mph for it to work properly. I have only tried it above 60 mph.