7 ms·

The Tesla’s stopping distance of 152 feet from 60 mph was far worse than any contemporary car we’ve tested and about 7 feet longer than the stopping distance of

The Tesla’s stopping distance of 152 feet from 60 mph was far worse than any contemporary car we’ve tested and about 7 feet longer than the stopping distance of a Ford F-150 full-sized pickup. That’s worrying, and almost as worrying is that Tesla says their braking is much faster. I’m sure plenty of fans will make comments about shorting stock, but this is Consumer Reports, and they have a very good reputation to protect. I’m not thrilled by this tidbit either. The Model 3’s stiff ride, unsupportive rear seat and excessive wind noise at highway speeds also hurt its road-test score. In the compact luxury sedan class, most competitors deliver a more comfortable ride and rear seat.

tshannon 8y ago
This part really intrigued me about the stopping distance: The Tesla spokeswoman says the company has the ability to update its vehicles over the air. “Unlike other vehicles, Tesla is uniquely positioned to address more corner cases over time through over-the-air software updates, and it continually does so to improve factors such as stopping distance,” she says. I'm curious the mechanism that makes that possible, or if it's just BS.
- Cthulhu_ 8y ago
  Why would you think it's BS? The Model S gets over-the-air updates all the time; if I recall correctly, they increased the ride height a while ago through an update after a car drove over a metal wotsit, causing a puncture in the battery compartiment and a fire. They can probably update the settings for the brakes as well, as long as the underlying mechanicals support it.
  - tw04 8y ago
    There are plenty of reasons why you would default to a lower ride height. What would be the purpose of intentionally making your brakes worse than an f150?
    - gnode 8y ago
      I don't think anyone's suggesting it was intentional. Parameters for managing the brakes may just have been set badly, or the anti-locking algorithm written poorly. A possible explanation is they may have optimised it to improve handling while braking.
  - blacksmith_tb 8y ago
    I think the implicit question is "can an OTA somehow improve braking performance - why isn't it optimal already?" not "do Tesla OTAs change other aspects of the car?"
    - Nasrudith 8y ago
      Electric motors and generators are essentially the same thing run in different directions. Run electricity through a motor and it generates motion while putting load on the power. Move a generator and it creates resistance as it extracts electricity. This also answers both how they can change it and why it is not already optimal. Actively using the motors to break causes it to use energy instead of recovering it. Hybrid drivers have long known to break gradually when possible to maximize battery recharge. It is possible they had an electric neophyte as a test driver. Fair enough if they were supposed to test from the perspective of someone new to hybrids and electric cars trying a Tesla as their first.
      - mshook 8y ago
        Not sure if you read the article but what they were testing is pretty much emergency braking from 60mph to full stop. So the goal is not regenerate the battery (and it doesn't matter if the driver was "an electric neophyte"), it's to brake hard and to repeat the process a couple of times to see if you get brake fade. From the article: Our testers get a car up to 60 mph, then slam on the brakes until the car comes to a stop. They repeat this multiple times to ensure consistent results. Between each test, the vehicle is driven approximately a mile to cool the brakes and make sure they don’t overheat.
        Nasrudith 8y ago
        Whoops. My mistake for giving into the temptation to segue after my explanation of what I did know.
      - detaro 8y ago
        What does "gradually braking to optimize battery recharge" have to do with an emergency stop?
  - tshannon 8y ago
    I never said I thought it was BS. I was curious what the physical mechanism to change the braking characteristics was. If there was no physical mechanism that I assume it's BS.
    - onesun 8y ago
      The car most definitely has software controlled anti-lock braking equipment, and likely has software controlled electric brake cylinders. Both of those things could plausibly be updated via an OTA update.
- deleted 8y ago
  [deleted]
- kbd 8y ago
  They improved acceleration via a software update[1] so it's plausible at least. [1] https://www.engadget.com/2016/11/16/tesla-p100d-software-performance-upgrade/ https://www.engadget.com/2016/11/16/tesla-p100d-software-per... Edit: why downvotes?
- ensignavenger 8y ago
  To me, it is disturbing. I get used to the way my vehicle handles, for it to suddenly change because of a software update could potentially be dangerous- but would almost certainly result in a trip to the mechanic for a checkup. Maybe they have a system for warning owners about these sorts of updates?
  - audionemesis 8y ago
    Well, yes. You get prompted to update your car (you can choose not to). And then after the update is complete, you get a Whats Changed prompt the next time you're in your car. Essentially a patch notes for your vehicle
    - whatok 8y ago
      For something as major as changing the way a car breaks, do you think "patch notes" (if read at all) are able to properly convey the magnitude of the change?
      - greglindahl 8y ago
        How do you know that the change is driver-visible? The change might only be for braking hard enough that the anti-lock feature kicks in... which most drivers don't do very often.
      - audionemesis 8y ago
        Yes? My 75D had an entire second shaved off of its 0 - 60 time. I was aware of the change and was able to deal with it just fine... I'm also not sure what the alternative you're imagining here is. Take it in to a shop just to have them install the update for you? I also don't see how this is any different than changing worn out brakes on an old ICE car. I had the brakes changed in my old '97 Accord, and the difference was noticeable when I pulled it out of the driveway. I think you need to give people a little more credit... Also, the Whats Changed prompt literally takes up the entire 17in touch screen. It's sort of hard to miss.
- gnode 8y ago
  My understanding is that car brakes can generally exert more braking force than the tire's grip on the road. A long stopping distance may represent a problem with the anti-lock braking system (which is likely software controlled, and can be updated over the air).
  - Animats 8y ago
    Interestingly, Waymo's self-driving car cannot be updated remotely.[1] As a security measure, Waymo deliberately did not install a data connection to allow that. Probably a good decision. [1] http://www.documentcloud.org/documents/4458000-Waymo-Driverless-AV-Application.html http://www.documentcloud.org/documents/4458000-Waymo-Driverl...
    - gnode 8y ago
      That's probably also to do with Waymo's cars being developed primarily for ride hailing fleets. With a private ownership model, requiring owners of variable technological faculty to manually apply updates would be less practical.
    - londons_explore 8y ago
      That was more a PR move than a real security measure. Signing updates and checking signatures is established technology to certify that updates come from the right place and are not tampered with. That and the updates are likely >10 GB, so you wouldn't want to download them over mobile data anyway.
  - magduf 8y ago
    It could, but it could also be a function of the car's weight (batteries are heavy) and the tires it comes equipped with from the factory. Poor tires will yield poor braking performance due to lack of grip.
    - dragontamer 8y ago
      But it can't be poor tires, because the Model 3's brakes were proper in the first test (~130 feet stopping distance). The same car with the same tires then had different braking behavior in every test after the first test. That's just odd.
abritinthebay 8y ago
"this is Consumer Reports, and they have a very good reputation to protect" CR doesn't have a very good reputation though? I mean... they used to. But their reputation is middling at best now.
- brianwawok 8y ago
  Who has better reviews for consumer goods?
JKCalhoun 8y ago
I understand Teslas are fairly heavy cars. That explains most of the problem I think.
- audionemesis 8y ago
  The Model S is in fact about as heavy as a Ford F150. However, if this braking result is consistent across all Model 3 vehicles, that's a bit worrisome. I'm also a little concerned with the other issues they had (ergonomics, wind noise, etc). From everyone I know that drives or has driven a Model 3, they've had amazing experiences as far as actual driving
ataturk 8y ago
I would not short TSLA no matter what. It is very difficult to short a stock and win. Possibly buy long expiration put options "lotto tickets" because there are so many ways Musk can game this and win for a lot longer than you imagine.

tshannon 8y ago

This part really intrigued me about the stopping distance: The Tesla spokeswoman says the company has the ability to update its vehicles over the air. “Unlike other vehicles, Tesla is uniquely positioned to address more corner cases over time through over-the-air software updates, and it continually does so to improve factors such as stopping distance,” she says. I'm curious the mechanism that makes that possible, or if it's just BS.

Cthulhu_ 8y ago
Why would you think it's BS? The Model S gets over-the-air updates all the time; if I recall correctly, they increased the ride height a while ago through an update after a car drove over a metal wotsit, causing a puncture in the battery compartiment and a fire. They can probably update the settings for the brakes as well, as long as the underlying mechanicals support it.
- tw04 8y ago
  There are plenty of reasons why you would default to a lower ride height. What would be the purpose of intentionally making your brakes worse than an f150?
  - gnode 8y ago
    I don't think anyone's suggesting it was intentional. Parameters for managing the brakes may just have been set badly, or the anti-locking algorithm written poorly. A possible explanation is they may have optimised it to improve handling while braking.
- blacksmith_tb 8y ago
  I think the implicit question is "can an OTA somehow improve braking performance - why isn't it optimal already?" not "do Tesla OTAs change other aspects of the car?"
  - Nasrudith 8y ago
    Electric motors and generators are essentially the same thing run in different directions. Run electricity through a motor and it generates motion while putting load on the power. Move a generator and it creates resistance as it extracts electricity. This also answers both how they can change it and why it is not already optimal. Actively using the motors to break causes it to use energy instead of recovering it. Hybrid drivers have long known to break gradually when possible to maximize battery recharge. It is possible they had an electric neophyte as a test driver. Fair enough if they were supposed to test from the perspective of someone new to hybrids and electric cars trying a Tesla as their first.
    - mshook 8y ago
      Not sure if you read the article but what they were testing is pretty much emergency braking from 60mph to full stop. So the goal is not regenerate the battery (and it doesn't matter if the driver was "an electric neophyte"), it's to brake hard and to repeat the process a couple of times to see if you get brake fade. From the article: Our testers get a car up to 60 mph, then slam on the brakes until the car comes to a stop. They repeat this multiple times to ensure consistent results. Between each test, the vehicle is driven approximately a mile to cool the brakes and make sure they don’t overheat.
      - Nasrudith 8y ago
        Whoops. My mistake for giving into the temptation to segue after my explanation of what I did know.
    - detaro 8y ago
      What does "gradually braking to optimize battery recharge" have to do with an emergency stop?
- tshannon 8y ago
  I never said I thought it was BS. I was curious what the physical mechanism to change the braking characteristics was. If there was no physical mechanism that I assume it's BS.
  - onesun 8y ago
    The car most definitely has software controlled anti-lock braking equipment, and likely has software controlled electric brake cylinders. Both of those things could plausibly be updated via an OTA update.
deleted 8y ago
[deleted]
kbd 8y ago
They improved acceleration via a software update[1] so it's plausible at least. [1] https://www.engadget.com/2016/11/16/tesla-p100d-software-performance-upgrade/ https://www.engadget.com/2016/11/16/tesla-p100d-software-per... Edit: why downvotes?
ensignavenger 8y ago
To me, it is disturbing. I get used to the way my vehicle handles, for it to suddenly change because of a software update could potentially be dangerous- but would almost certainly result in a trip to the mechanic for a checkup. Maybe they have a system for warning owners about these sorts of updates?
- audionemesis 8y ago
  Well, yes. You get prompted to update your car (you can choose not to). And then after the update is complete, you get a Whats Changed prompt the next time you're in your car. Essentially a patch notes for your vehicle
  - whatok 8y ago
    For something as major as changing the way a car breaks, do you think "patch notes" (if read at all) are able to properly convey the magnitude of the change?
    - greglindahl 8y ago
      How do you know that the change is driver-visible? The change might only be for braking hard enough that the anti-lock feature kicks in... which most drivers don't do very often.
    - audionemesis 8y ago
      Yes? My 75D had an entire second shaved off of its 0 - 60 time. I was aware of the change and was able to deal with it just fine... I'm also not sure what the alternative you're imagining here is. Take it in to a shop just to have them install the update for you? I also don't see how this is any different than changing worn out brakes on an old ICE car. I had the brakes changed in my old '97 Accord, and the difference was noticeable when I pulled it out of the driveway. I think you need to give people a little more credit... Also, the Whats Changed prompt literally takes up the entire 17in touch screen. It's sort of hard to miss.
gnode 8y ago
My understanding is that car brakes can generally exert more braking force than the tire's grip on the road. A long stopping distance may represent a problem with the anti-lock braking system (which is likely software controlled, and can be updated over the air).
- Animats 8y ago
  Interestingly, Waymo's self-driving car cannot be updated remotely.[1] As a security measure, Waymo deliberately did not install a data connection to allow that. Probably a good decision. [1] http://www.documentcloud.org/documents/4458000-Waymo-Driverless-AV-Application.html http://www.documentcloud.org/documents/4458000-Waymo-Driverl...
  - gnode 8y ago
    That's probably also to do with Waymo's cars being developed primarily for ride hailing fleets. With a private ownership model, requiring owners of variable technological faculty to manually apply updates would be less practical.
  - londons_explore 8y ago
    That was more a PR move than a real security measure. Signing updates and checking signatures is established technology to certify that updates come from the right place and are not tampered with. That and the updates are likely >10 GB, so you wouldn't want to download them over mobile data anyway.
- magduf 8y ago
  It could, but it could also be a function of the car's weight (batteries are heavy) and the tires it comes equipped with from the factory. Poor tires will yield poor braking performance due to lack of grip.
  - dragontamer 8y ago
    But it can't be poor tires, because the Model 3's brakes were proper in the first test (~130 feet stopping distance). The same car with the same tires then had different braking behavior in every test after the first test. That's just odd.

abritinthebay 8y ago

"this is Consumer Reports, and they have a very good reputation to protect" CR doesn't have a very good reputation though? I mean... they used to. But their reputation is middling at best now.

brianwawok 8y ago
Who has better reviews for consumer goods?

JKCalhoun 8y ago

I understand Teslas are fairly heavy cars. That explains most of the problem I think.

audionemesis 8y ago
The Model S is in fact about as heavy as a Ford F150. However, if this braking result is consistent across all Model 3 vehicles, that's a bit worrisome. I'm also a little concerned with the other issues they had (ergonomics, wind noise, etc). From everyone I know that drives or has driven a Model 3, they've had amazing experiences as far as actual driving

ataturk 8y ago

I would not short TSLA no matter what. It is very difficult to short a stock and win. Possibly buy long expiration put options "lotto tickets" because there are so many ways Musk can game this and win for a lot longer than you imagine.