
Tesla Model 3 Gets CR Recommendation After Braking Update - fmihaila
https://www.consumerreports.org/cars-tesla-model-3-gets-cr-recommendation-after-braking-update/
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vlozko
I'm bothered by the fact that it took Consumer Reports testing to discover
this issue and to have it fixed. Where was Tesla's QC on this before all this?
The CR break tests don't appear to be anything unusual.

~~~
sunstone
It's not quite as bad as it seems. The first high speed stop CR did produced
the expected and acceptable result. But when they repeated the test they
started to get poor results. Under normal driving conditions you don't often
repeatedly slam on the brakes from 60mph. Now this isn't a complete absolution
of Tesla under the circumstances but it does go some way to explaining how
this software bug got into the wild when it shouldn't have.

~~~
dpark
That’s still pretty bad, honestly. All it took was repeated testing to trigger
the issue? That indicates that either Tesla’s testing was woefully
insufficient here or that they took a late change to braking behavior without
a proper re-testing regimen.

I can actually understand the latter possibility, but it’s still a giant screw
up.

~~~
sunstone
Yes I agree with you. I expect they made a code change in order to stress test
a different component of the braking system and then forgot to revert that
change.

If so, it's a big screw up for this kind of product development. But still,
it's much better than "these brakes have a design flaw and can never work
properly and we don't know how to make cars".

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netsharc
So, OTA software update improved the brakes (dear commenters, please spell
this word correctly). Why not have the brakes with that strength from the
beginning? If I were to speculate, could it be because this setting would
cause high brake wear on the long run?

And, what's stopping them from selectively applying this setting? Heh,
Volkswagen would probably have loved this capability a few years ago.

~~~
omarforgotpwd
So, Model 3 has regenerative brake (uses magnetic resistance to slow car) and
regular brakes that every other car has. I believe the tradeoff / timing about
when to switch between the two braking systems was slightly off, favoring more
energy efficiency rather than the best stopping distance. When this was
pointed out they simply adjusted their algorithm for a better overall
tradeoff.

~~~
jonknee
It's extremely embarrassing/telling that it took Consumer Reports to point out
their new car doesn't stop well.

~~~
blevin
Alternately, it's amazing and inspiring what just happened; other high-end car
makers with a century of experience have shipped imperfect brakes for years
(1) and only redesigned them on new models in response to complaints. Tesla,
by comparison, is applying the Apple model (when Apple is at its best) of
continuous over-the-air product improvement, which can change one’s sense of a
product's value for money.

1\. MERCEDES CANCELS BY-WIRE BRAKE SYSTEM; DECISION A BLOW TO TECHNOLOGY'S
FUTURE. "When the system failed, the hydraulic system took over. But that
resulted in a longer stopping distance and additional brake pedal effort by
the driver." [http://autoweek.com/article/car-news/mercedes-cancels-
wire-b...](http://autoweek.com/article/car-news/mercedes-cancels-wire-brake-
system-decision-blow-technologys-future)

~~~
jonknee
Mercedes had a hardware problem and Tesla had a software problem, I really
don't see how this is a win for Tesla. Tesla has done physical recalls before
as well, not everything is a software bug.

[https://repairpal.com/recall/05V133000](https://repairpal.com/recall/05V133000)

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simion314
What prevents a new update to revert this or cause other safety problem?

Pushing updates in a rush is not a good sigh for critical software.

~~~
colinbartlett
I'd like to think they have some kind of automated CI with a huge warehouse
full of cars that automatically drives around and tests everything with each
Git push.

~~~
jonknee
They sort of do, it's the general public.

~~~
empath75
And they've only killed a few people so far.

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colinbartlett

      - const brakingDistance = 152;
      + const brakingDistance = 133;

~~~
baseethrowaway
braking

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colinbartlett
oh, right... thank you! (edited)

~~~
mikeash

      const breakingDistance = warrantyMiles + 1;

~~~
hoffbrau99
>> const breakingDistance = warrantyMiles + 1;

const brakingDistance = warrantyMiles + 1;

~~~
howenterprisey
Read the chain of comments again

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minhazm
It was an ABS issue for anyone wondering.
[https://twitter.com/elonmusk/status/998778751767871488?lang=...](https://twitter.com/elonmusk/status/998778751767871488?lang=en)

~~~
vlozka
Controlling the ABS hydraulic modulator and ABS diagnostic bleed are one of
the most dangerous cyber-attacks that can be performed on a car.

The fact that these systems are (indirectly) connected to the Internet is
irresponsible.

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stephengillie
> _In retesting after the software update was downloaded, the sedan stopped in
> 133 feet from 60 mph, an improvement of 19 feet._

Combining from a previous thread[0]:

    
    
      Car           distance (feet)
      Model 3(orig) 152
      Model 3 (new) 133
      F-150         129
      Model X       127
      Camry Hybrid  125
      F-150 Lariat  119
      Chrysler 300S 109
    

It's noteworthy that the stopping distance is still longer than the heavier
Model X.

[0][https://news.ycombinator.com/item?id=17124967](https://news.ycombinator.com/item?id=17124967)

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skolos
Did they do it by reducing use of regenerative braking? Does it mean now that
M3's brake pads will wear even more quickly? It looks like they already were
wearing off faster than expected [1].

[1] [https://www.autoevolution.com/news/tesla-model-3-brake-
pads-...](https://www.autoevolution.com/news/tesla-model-3-brake-pads-
destroyed-after-nine-miles-of-laguna-seca-124324.html)

~~~
jimrandomh
That link is about brake performance on a race track at speeds greater than
100mph. I'm not sure what "expected" is in that context, and I doubt the
results generalize to more normal usage.

~~~
azinman2
CR article mentions 60mph, not 100.

~~~
jimrandomh
I was referring to the Autoevolution post, not the Consumer Reports article.
It specifically mentions a maneuver at 103.9mph.

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ISL
A question for those in the know: To what extent do other auto manufacturers
make this level of in-line changes?

As someone who has only ever bought used cars, the prospect of substantial in-
line changes for a specific model year is quite daunting. With Tesla, it would
appear that they are making substantial changes in build
technique/quality/parameters weekly...

~~~
dsfyu404ed
Performing code changes/updates whenever a car comes into the dealership is
pretty standard practice. OTA updates are a technical capability many
manufactures have but I'm not sure the extent to which they're used.

~~~
exhilaration
My understanding is that almost no one else does OTA updates because their
dealer networks demand that any repairs or updates be performed by dealers.
The legacy car manufacturers are (sadly) at the mercy of their dealers.

~~~
benjohnson
Newer FCA products can update OTA - Our 2015 Dodge Durango updated a month
ago.

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mchahn
I know there is a 99.9% chance that my paranoia is just paranoia, but when I
first read this I thought tesla just changed the car's behavior to work better
on CR's specific tests. The diesel fiasco has scarred me.

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woodandsteel
The practical question is how good the Model 3 will be when they get
production up to the point where the large number of people who want to buy
one are actually able to do so.

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avs733
So to clarify a bit...maximum/emergency braking like this is not limited by
regen or by the hydraulic brakes. It is limited by tires, grip, and weight
transfer.

~~~
dpark
Clearly in this case it was limited by a software bug/limitation. Tesla did
not push an over the air update that changed the tires, grip, or weight
transfer.

(Actually, I guess they did change the weight transfer, by increasing
deceleration.)

~~~
avs733
oh totally agreed. What I find confounding is that up until now the limit on
braking performance appears to not have been tire grip but software.

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SubiculumCode
Cars are not a Flappy Bird app: Crashing matters.

This clearly points to a culture inside Tesla of a lackadaisical concern for
product safety testing. I say that as a big fan of Tesla and the overall
vision Musk and his companies are pursuing.

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mherrmann
"We fixed it so it brakes."

