Braking distance concern by Consumer Reports

[Zaphod]

How does that explain the big difference in stopping distance though? Is the software wrong, or is the hardware not capable and Tesla is trying to tweak the software to compensate?

I'm sure the hardware is capable, although sounds like the brake pads themselves are not up to high abuse. I wouldn't say software is wrong, but as I understand it may not be totally optimized either in actuation timing or application force, maybe both. Slower actuation and less force will lead to longer stopping distances. Too quick of application and too much force could cause tires to slide or brakes to lock and also lead to longer distances. The optimum will be in the middle somewhere.

 

[nvx1977]

"Looks like this can be fixed with a firmware update. Will be rolling that out in a few days. With further refinement, we can improve braking distance beyond initial specs. Tesla won’t stop until Model 3 has better braking than any remotely comparable car."

I’d like to give Elon the benefit of the doubt on this one. While it seems unlikely that a firmware update alone would cause the Model 3 to best the Audi or BMW brake specs, I’m inferring he means Tesla is committed to continuous improvement longer term until the Model 3 specs do surpass them.

My interpretation of that tweet is that:

1) the firmware update that contains the fix will address the variability and inconsistency in emergency braking performance in the entire fleet.

2) in examining the software side of things for this fix, Musk has found a bit more room to optimize braking performance, and he thinks when that is done, Model 3 braking will perform better than originally spec'd.

Whether #2 happens in the same firmware release as #1 is TBD, but either way, pretty promising stuff.

For those who don't know, Musk once improved the efficiency of the Model S through a firmware update. Engineering just found a better solution and they pushed it to the entire fleet.

 

[PhantomX]

I'm sure the hardware is capable, although sounds like the brake pads themselves are not up to high abuse. I wouldn't say software is wrong, but as I understand it may not be totally optimized either in actuation timing or application force, maybe both. Slower actuation and less force will lead to longer stopping distances. Too quick of application and too much force could cause tires to slide or brakes to lock and also lead to longer distances. The optimum will be in the middle somewhere.

If that's the case, I am quite surprised that wasn't caught in testing. I would have assumed Tesla put their test cars through some harsh tests to identify issues. I hope they didn't just drive around the street in normal condition and then release it to the customer.

 

[N5329K]

Update:

Robin

 

[EchoDelta]

Doesn't that freak out anybody that our ability to break or speed up can be drastically changed with one software push? What if the pusher is malicious or a mistake is made?
I'm all for improving windshield wipers or mirrors, but this is actually kind of scary... I'm really hoping they have proper security measures in place. B/c if something bad happens due to a software push that will be the end of Tesla. Or end of OTA updates for all future manufacturers.

Yeah but it's not unique. I work in medical devices and that's why you are super careful and pay the best to help you w security and reliability of remote updates.

 

[geoffreak]

Update:

Robin

This video probably deserves it's own thread. There's a ton of new info in this video, all reportedly from a direct call from Elon.

A few highlights:

• They've recently changed the following production items in the last two months: suspension dampers (before was springs), glass (for lower noise), and seats (for comfort).
• Braking changes software update should be released as early as this weekend.
• The Model 3 should be getting a key fob. (Not specified if this will work with older cars.)

  We really need to provide a normal key to the customers of this car

Here's the thread in the subreddit about it. One of the responders corroborates the Model 3 key fob story.

 

[Electricfan]

I'm legitimately confused about what Elon actually means with this tweet:
"Looks like this can be fixed with a firmware update. Will be rolling that out in a few days. With further refinement, we can improve braking distance beyond initial specs. Tesla won’t stop until Model 3 has better braking than any remotely comparable car."

I tweeted this back (no answer, of course):
"Does this mean after the update that my Model 3 will brake quicker than the Audi A4 (105 ft) or BMW i3 (108ft)? Fingers crossed! Thanks for an amazing car!"

So what is everyone's interpretation of his tweet? Certainly an Audi A4 and BMW i3 are "remotely comparable" cars?

LOL! Join the club!

My interpretation is Tesla will make whatever software/hardware changes are needed, at Tesla's expense, to make this problem go away. And I read somewhere he wrote "at our expense", didn't I? So I say "Yes", you should expect improvements to your Model 3's braking performance. Whether it will be in this decade or not...

 

[D3xDt3Reaction]

My interpretation of that tweet is that:

1) the firmware update that contains the fix will address the variability and inconsistency in emergency braking performance in the entire fleet.

2) in examining the software side of things for this fix, Musk has found a bit more room to optimize braking performance, and he thinks when that is done, Model 3 braking will perform better than originally spec'd.

Whether #2 happens in the same firmware release as #1 is TBD, but either way, pretty promising stuff.

For those who don't know, Musk once improved the efficiency of the Model S through a firmware update. Engineering just found a better solution and they pushed it to the entire fleet.

As I do a sort of mental "first principles" analysis of ABS, I think you may have a point about firmware having potential for improved braking performance beyond just the fix for the variability CR uncovered. I'm not an expert on ABS, but I do know a little about firmware.

In my mind, the basic task of an "ideal" ABS is to dynamically modulate braking pressure such that the tire is always rolling and not sliding, but only just. If the ABS could magically determine beforehand the proper braking pressure over time as a function of all system/environmental dynamics, then minimum braking distance would be limited only by the interface between the tire and the surface. All things being equal, two cars with "ideal" ABS tested on the same surface under the same conditions would therefore be limited only by the coefficients of friction of their tires. And if they had the same tires, they should stop in exactly the same distance.

In practice, however, ABS can't do magic to determine proper braking pressure in advance and has to constantly "guess" based on when a tire starts to slip. Other real world hardware-related factors like sensors and closed loop latency also come into play that make the system less than ideal. Overall, whether or not a Model 3 can best some other car in braking performance depends on more than just firmware, i.e. tire performance and hardware, although firmware plays a significant role. Here's hoping they can do a lot more with just firmware.

 

[Trevor B]

If they retest with CR and fail again that will be bad news for Tesla. Also this is a press car. What auto maker would not put it's best car for the press, unless they just wanted to have an excuse if it did poorly.

You have no idea how CR tests their cars ...

 

[Brando]

You have no idea how CR tests their cars ...

You could try reading how it is done.
You could use internet searching to find what to read. Very handy this internet thing.

To save you the effort, here are some things I found:
2012 Annual Auto Issue: Best cars for braking
How Consumer Reports Tests Cars
Best Car Safety Performance

PS- I know some other people actually read.
</sarcastic alert> have fun Trevor and enjoy -
(many things you can't control - but how you react is one thing you can control - old man's opinion)

 

[drawfour]

You could try reading how it is done.
You could use internet searching to find what to read. Very handy this internet thing.

To save you the effort, here are some things I found:
2012 Annual Auto Issue: Best cars for braking
How Consumer Reports Tests Cars
Best Car Safety Performance

PS- I know some other people actually read.

@Trevor B was quoting @adaptabl who said "Also this is a press car.", which was bolded by Trevor in the quote. That is clearly the point he was responding to.

Consumer Reports does not use "press cars", which are cars given to the press to write reports about. Consumer Reports buys their cars themselves, to make sure they don't get one that is specifically produced for the press. They want a regular one that a regular consumer would get.

 

[Brando]

@Trevor B @drawfour

oops, insert foot into mouth yet again.
reading - perhaps
reading well - still working on it, it seems

 

[GuyDude]

I just got another update 18.20

Could it be the brake fix!?

 

[GuyDude]

I just got another update 18.20

Could it be the brake fix!?

Correction : 18.13

Not 18.20

 

[chinnam3]

Does any current M3 owners feel that the cars braking capabilities are any less capable vs. any other car that you drive?

Tesla shares hit by Consumer Reports criticism

From Consumer Reports...
Tesla's stopping distance of 152 feet when braking at 60 mph was far worse than any contemporary car tested by the magazine and about seven feet longer than the stopping distance of a Ford F-150 full-sized pickup.

Responding, a Tesla spokesperson said: "Tesla's own testing has found braking distances with an average of 133 feet when conducting the 60-0 mph stops using the 18" Michelin all season tire and as low as 126 feet with all tires currently available.

I do not know the brake distance as I haven't tried full emergency braking, but for sure braking feels sub-par especially when it transitions from Regen to Brake pads as if brakepads somehow released and reapplied with glazed pads. Feel is nowhere close to my previous ride BMW E90 with OEM pads.

I am not new to regen to brakepad switch over (as we have hybrid also), but this is distinctly alarming atleast on my car. Now, I am getting used to that though.

 

[Msjulie]

I thought Tesla did not use blended breaking - ie regen is regen and friction braking is added on top by the driver (or other) vs some cars like our previous Fiat 500e that used regen down to 8mph or so or if a sudden hard brake pedal application; you could feel that car switch to really using the brakes

Does Tesla now use blended braking?

 

[hiroshiy]

I thought Tesla did not use blended breaking - ie regen is regen and friction braking is added on top by the driver (or other) vs some cars like our previous Fiat 500e that used regen down to 8mph or so or if a sudden hard brake pedal application; you could feel that car switch to really using the brakes

Does Tesla now use blended braking?

As far as I know, no.

BTW Elon tweeted this.
Elon Musk on Twitter
So fix is underway.

 

[nvx1977]

I thought Tesla did not use blended breaking - ie regen is regen and friction braking is added on top by the driver (or other) vs some cars like our previous Fiat 500e that used regen down to 8mph or so or if a sudden hard brake pedal application; you could feel that car switch to really using the brakes

Does Tesla now use blended braking?

You are correct. There is no transition from regen to friction. They are completely independent of each other. However when you press the brake pad, both regen and friction are working at the same time.

 

[Msjulie]

They are completely independent of each other

Matches my experience and based on other ev's I have driven, my preference..

 

[Msjulie]

Elon Musk on Twitter

The geek in me wishes there were some tech details provided...