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Traffic-Aware Cruise Control "Panic Stop Mode"

Traffic-Aware Cruise Control "Panic Stop Mode"

I love Traffic-Aware Cruise Control about 99% of the time, especially in dense traffic where the speed keeps fluctuating for whatever random reasons it does in dense traffic. The car does a great job adjusting its speed to the varying traffic, and maintaining a comfortable following distance. And when the traffic ahead comes to a full stop, so does the car, smoothly and safely.

Except...

This all works great when we are sort of part of the traffic, following another car. The exception is when traffic has stopped up ahead, but so far we're still moving at speed limit. It's clear where I am, but seconds ahead it won't be. In this situation it's scary for me and likely for the driver ahead, if they happen to be looking in their mirrors. The Tesla maintains full speed long after I would have begun slowing. I'm unwilling to play chicken with the computer to see whether it will really stop in time, so I brake on my own.

One, this confirms what Tesla says about we drivers are ultimately responsible for safe operation.

Two, I wish it looked farther ahead and did a better job in this sort of situation.

Lorenzryanc | October 29, 2018

I agree... it feels TOO aggressive to me, but every time it does stop (so far). There seems to be a pattern just like you explained. Stop and go it's fine. Speed up for 3-5 seconds to limit, it'll leave the stop-go traffic mode and go to regular mode. Perhaps change follow distance? I've noticed that it still does the aggressive braking, just earlier. I've gotten in the habit of pushing up on the stalk to allow regen to take over earlier and reengage after "hold". I'm sure in the future the car will use the 5 cars in front of you to determine how to stop smoother, until then, sign me up to be a guinea pig (aka BETA).

The 99% makes it worth it.

andre | October 29, 2018

I wonder if this is influenced by the follow distance setting. For me, the car seems to begin braking just before I think “nope, I’m taking over now.”

CharleyBC | October 29, 2018

@Lorenzryanc: I agree, it's worth it. Like so many things that I like a lot, I want to make it even better!

rxlawdude | October 29, 2018

Easiest way to remember: If the vehicle in front of you is NOT being tracked (not there on display), AP will NOT stop for it when AP encounters suddenly stopped traffic.

jdcollins5 | October 29, 2018

V9 TACC does a better job of sensing a stopped or slowing car ahead than V8. V9 is a lot closer to what I would do.

I normally would take over with V8 before I finally gained enough confidence that it would eventually start slowing down, albeit braking very aggressively.

M3BlueGeorgia | October 29, 2018

Everytime I've run into this situation, the car has safely stopped.

Even on a divided highway doing 55mph coming up onto cars stopped at a red light in my lane....

Observations:
- Can be a bit nerve racking at times, and sometimes I just brake myself
- Works best when the road is flat and straight
- Works worst when approaching the car ahead from over a rise
- Approaching stopped traffic on a curve can be a bit nerve wracking :-)

IMHO you'll find it always seems to work, but in certain scenarios you'd be well advised to brake because you can anticipate before it does, and therefore avoid an abrupt braking scenario, especially in slippery road conditions.

kinman.chung | October 29, 2018

I usually turn down the set max speed to a little more than the flow, in this situation.

wayne | October 29, 2018

At highway speeds I don’t think the computer can see far enough ahead to use regenerative breaking and slow down gradually for a stopped car. Since I can see this coming I just kick it out of TACC. Some times you have to drive yourself.