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Forward collision warning

DeltaOne

Member
Mar 19, 2021
69
47
Mount Airy, MD
We've owned our Model 3 for two weeks. Today, out for a ride, the Forward Collision Warning and Automatic Emergency Braking did something that seemed wrong.

Driving north on a two lane road. Up ahead a big SUV pulls out from the right side, crosses in front of me, and heads south. There was plenty of room. I had the cruise control on but if not I wouldn't have let up on the accelerator at all. My car braked pretty hard. It all happened so fast I didn't have time to look at the touchscreen and I didn't notice a warning chime. My wife was in the passenger seat and did hear the warning chime.

I quickly looked in the rear view mirror, afraid we were going to be rear-ended. Luckily, no one was behind us.

Home now, I check the owner's manual and learn that Automatic Emergency Braking will release the brakes when the car has slowed down by 30 MPH. Or by turning the steering wheel, press/release the brake pedal, accelerate hard or the object is no longer detected.

I saw that Forward Collision Warning is adjustable. Late, Medium and Early. Maybe the "Late" setting would be better? Any advice?
 

tstolze

Member
Oct 9, 2020
239
368
OFallon, MO
We have had it happen a couple times now in 5 weeks of driving our M3.
After a couple of these events, I have gone back and watched the dashcam video and they were all closer than I thought at the time it happened.
We decided we would have let off the gas in an ICE car and been ready to apply the brakes, it's a tough call, it is almost as if there's extra caution built in just in case the vehicle pulling out has a problem.
 
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Knightshade

Well-Known Member
Jul 31, 2017
11,629
15,669
NC
We've owned our Model 3 for two weeks. Today, out for a ride, the Forward Collision Warning and Automatic Emergency Braking did something that seemed wrong.

Driving north on a two lane road. Up ahead a big SUV pulls out from the right side, crosses in front of me, and heads south. There was plenty of room. I had the cruise control on but if not I wouldn't have let up on the accelerator at all. My car braked pretty hard. It all happened so fast I didn't have time to look at the touchscreen and I didn't notice a warning chime. My wife was in the passenger seat and did hear the warning chime.

I quickly looked in the rear view mirror, afraid we were going to be rear-ended. Luckily, no one was behind us.

Home now, I check the owner's manual and learn that Automatic Emergency Braking will release the brakes when the car has slowed down by 30 MPH. Or by turning the steering wheel, press/release the brake pedal, accelerate hard or the object is no longer detected.

I saw that Forward Collision Warning is adjustable. Late, Medium and Early. Maybe the "Late" setting would be better? Any advice?


Realistically, Teslas basic AP features (TACC and Autosteer) are meant for highways where cross-traffic does not exist.

They operate on the assumption all traffic is going the same direction as you-- so if it sees a vehicle sideways ahead in your lane, it assumes someone is blocking your lane, not in the middle of crossing it in a 90 degree turn, and brakes.


Page 83 owners manual said:
WARNING: Do not use Traffic-Aware Cruise control on city streets or on roads where traffic conditions are constantly changing

Autosteer is even more explicit about this:


Page 89 said:
Autosteer is intended for use only by a fully attentive driver on freeways and highways where access is limited by entry and exit ramps



The good news, assuming you have FSD, is the beta software that's allegedly going to be available very shortly will do 2 things:

Enable city streets code that understands things like cross traffic properly

and

Removes use of radar as a sensor input, which often causes unneeded braking events
 

DeltaOne

Member
Mar 19, 2021
69
47
Mount Airy, MD
Realistically, Teslas basic AP features (TACC and Autosteer) are meant for highways where cross-traffic does not exist.

They operate on the assumption all traffic is going the same direction as you-- so if it sees a vehicle sideways ahead in your lane, it assumes someone is blocking your lane, not in the middle of crossing it in a 90 degree turn, and brakes.

Page 83 owners manual said:
WARNING: Do not use Traffic-Aware Cruise control on city streets or on roads where traffic conditions are constantly changing
Page 89 said:
Autosteer is intended for use only by a fully attentive driver on freeways and highways where access is limited by entry and exit ramps

I see. I've been through the user manual twice, but I guess I need to read through it again. Maybe a little slower and more thoroughly this time.

Fancy new car with great technology. It was too much to resist, I guess. Thinking back on yesterday's incident, had I been in my old ICE car, it never would have crossed my mind to use the cruise control on a road like that.

On a previous day, we had an experience on another two lane road where the Tesla started braking for a green traffic light. I knew to hit the accelerator and we continued through the intersection. But that was a little unsettling too. I've always thought one of the main causes of accidents is cars stopping in places that other drivers wouldn't expect there to be a stopped car. So I definitely don't want my Tesla stopping in a place where other drivers won't be expecting it and maybe not paying 100% attention.

But that makes perfect sense. TACC and AP for highway use only.

Many thanks for your post!
 

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