Braking distance concern by Consumer Reports

[dhanson865]

Summer tires stop faster in wet conditions than all season tires. I’m not sure about mud but it seems silly to worry about such a rare use case.
133 feet is close to what every other car gets when equipped with all season tires. The cars getting much better distances are using summer tires.

Up until the point they hyrdroplane. Summer Performance tires often have a tread pattern that doesn't evacuation water as well as All Season tires.

To add to the fun they often have poor treadwear ratings meaning you end up driving on less tread for the same amount of miles.

Average out the traction they have over the life of the tire and you see they don't always have the traction they have when new and that changes the comparison.

 

[SageBrush]

You know what’s fun? Going back to the beginning of a thread and rereading it. Especially when there’s been a quick turn around. Very enlightening to see what people say about a situation they know nothing about and how their narrative does or does not change, their emotional state, their intellectual state etc...

I followed your advice. I did not find any posts of mine (I think they are in a parallel thread) to grade but I found yours.

You get an 'A'

 

[Knightshade]

Up until the point they hyrdroplane. Summer Performance tires often have a tread pattern that doesn't evacuation water as well as All Season tires.

This is simply untrue.

I previously quoted a tire vendor saying you're wrong.


Here's a tire maker telling you you're wrong

Summer Tires vs. All Season Tires | Bridgestone Tires

Surprising to some, summer tires provide better performance in wet driving conditions, thanks to unique tread patterns that help evacuate water and resist hydroplaning.

here's another tire maker telling you you're wrong-
When do you need Summer Tires, Winter Tires or All Season Tires?

They include graphs detailing the superior performance of summers to all seasons in wet conditions, including resistance to aquaplaning.


Here's Edmonds.com performing similar testing also proving you wrong-
Tire Test: All-Season vs. Snow vs. Summer

The all seasons hydroplaned much more easily than the summer tires did in wet testing- and also took a lot longer to stop the car than the summer tires.



So once again-

Brakes don't stop cars- tires do.

Upgrading your brakes is not a way to make the car stop shorter.

Upgrading your tires is.

Use proper seasonal tires (that's summers when it's above 40-45 (varies by tire- the PS 4S for example is fine at 40 and above) and winters when it's below that) and you'll enjoy shorter braking distances and better acceleration and handling 100% of the time compared to the all-seasons that come on the Model 3.

 

[u00mem9]

I think you're missing the point. Every car manufacturer finds bugs after the car is released, which until now generally required a trip to the dealer. Given you'd require multiple panic stops in a row to figure out this braking problem, I'm not surprised Tesla didn't see it during development. 1)you'd have to test sequential panic stops, which is not a normal driving experience, 2) you'd have to notice that the subsequent stops were 20 feet longer (we aren't talking brake failure here). The story here is really how fast the problem was fixed at the end user. I find it an exciting development and worthy of praise.

That’s because you have no idea how development normally works. The type of usage tested here is (contrary to this thread’s amateur hour commentary) well known and tested during development.

Tesla sold these cars before development was finished. Yes, OTA updates make this less difficult to remedy and all OEMs will use this technique in the future to minimize recall costs...but this isn’t some corner case brake usage. Tesla had you test driving dev cars. Some of us get paid nicely to take that risk. If this had ended in loss of life, instead of a bad review, the cult would be here announcing that the driver should have never been in an emergency braking event.

Like I said, surreal to see people praising open negligence.

 

[SageBrush]

... the cult would be here announcing that the driver should have never been in an emergency braking event.

Not quite. We would say that it was a poor idea to go do it again for the sake of reproducibility.

 

[Brando]

The more I learn/see about software development the less surprised I am about bugs.
I'd suspect some extra attention to regression testing is happening at Tesla.
I'm sure I'm not the only one that would be fascinated about the details of this bug and know more about how ABS has developed over the last 30 years.

In addition to seeing SageBrush reaction time/distance added to brake performance testing and the "LOL texting variable" added I am now thinking I'd like to see gross vehicle weight added from driver only + 100 Kg all the way to Max. vehicle weight. I had never considered all the variable to vehicle stopping before reading this thread. Certainly someone must have done stop testing with these details added?

In spite of my emotional reactions to auto deaths it does impress me how much safer vehicle travel is today compared to 1960s. Still a leading killer of 16-24 year olds and surprisingly vehicle death rates up almost 15% the last couple of years (cell phones or increased per capita drug in take of all kinds suspected by many). ~1,200,000 deaths worldwide per year 12 million a decade? what a waste.

55 mph speed limits in Metro areas and more effort to avoid traffic jams seems in order.
Lost time from lower speed limits would seem trivial to lost time from traffic slow downs, right?

</end of too long a post>

 

[electronhauler]

Is this correct? 1.5 seconds is an eternity and I can't see even an elderly person having that slow of a reaction time.

It's not just pure reaction.. it's the time to make a decision too. The best everyday example is to observe the front vehicles at a red light. when the light changes to green, the alert driver will move in under a second, but most exceed a second, and sometimes it's 2 or 3! The study at Monash found that teenage drivers, and the over 70's were the slowest to make a decision and react. The teenagers have much better 'fast twitch' reaction but they took a long time to make a decision to react.

 

[voip-ninja]

It's not just pure reaction.. it's the time to make a decision too. The best everyday example is to observe the front vehicles at a red light. when the light changes to green, the alert driver will move in under a second, but most exceed a second, and sometimes it's 2 or 3! The study at Monash found that teenage drivers, and the over 70's were the slowest to make a decision and react. The teenagers have much better 'fast twitch' reaction but they took a long time to make a decision to react.

Increasingly for starting up from stop lights I see delays of over 3 seconds for the very first car to move. When I am parallel to drivers at multilane turns I often see the driver immediately, the moment they stop at the light get their phone out and start playing with it. Then if they are the lead driver in their lane they need enough time to recognize that the light is green (sometimes because the driver in another lane moved or someone finally honks at them), mentally disconnect from the phone, scan the intersection and proceed.

If I had to hazard a guess it would be that cell phone use, especially smart phone, has had a real and measurable effect on traffic congestion in cities.

 

[SigNC]

It's not just pure reaction.. it's the time to make a decision too. The best everyday example is to observe the front vehicles at a red light. when the light changes to green, the alert driver will move in under a second, but most exceed a second, and sometimes it's 2 or 3! The study at Monash found that teenage drivers, and the over 70's were the slowest to make a decision and react. The teenagers have much better 'fast twitch' reaction but they took a long time to make a decision to react.

this drives me insane. About as bad as when somebody is waiting to turn left and they have to wait for the car to completely clear them before they even begin to make their movement.

 

[electronhauler]

this drives me insane. About as bad as when somebody is waiting to turn left and they have to wait for the car to completely clear them before they even begin to make their movement.

I wondered about that too, and found that in some jurisdictions you can only start a left turn if the exit path is clear. In the UK. (turning right) you will fail your driving test if you start the turn before you can see down the road you intend to turn on to. The sweeping turn, which you often see in the US is not allowed.

 

[Brando]

Reaction times vary greatly with situation and from person to person between about 0.7 to 3 seconds (sec or s) or more. Some accident reconstruction specialists use 1.5 seconds. A controlled study in 2000 (IEA2000_ABS51.pdf) found average driver reaction brake time to be 2.3 seconds. [others estimate 2.5-2.7 seconds]

https://korkortonline.se/en/theory/reaction-braking-stopping/
http://www.webpages.uidaho.edu/niat...esign/theoryandconcepts/BrakeReactionTime.htm

 

[Twiglett]

Wow I saw fifteen pages of discussion for an issue that was resolved weeks ago.
I was surprised until I remembered I was here

 

[NoBeard]

Though in this case they may have been somewhat credible, once you've seen this video you'll likely trust them as much as I have since I saw it years ago.

<iframe width="560" height="315" src="

" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

 

[Jack007]

This is awesome actually, get all the bugs worked out so when, if, we can afford to buy a 3 (after the S is paid off)
It will be KICK A$$ PERFECT.

 

[mongo]

No, not really. I have read every article, including the ones you posted, and I can't find any that give an exact reading for the first emergency stop on subsequent days. Just that they coudn't repeat the 126 feet, and tests were as bad as 152 feet. You can draw your own conclusions, and fill in the gaps if you have the actual CR test data, but I'm done beating this dead horse.

Part of nuf said was getting the discussion moved to an appropriate thread.

The 126 number wasn't from CR, it was Tesla's data with better tires. The first post on this thread:

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.

CR got ~132 on initial test and 150s after that.
After the SW fix, distances stayed in the 130s:
Elon Musk on Twitter

Also, firmware fix for upgraded brake performance on standard Model 3 started rolling out yesterday. Should improve braking distance by ~20 ft for repeated heavy braking events. Thanks @ConsumerReports for excellent critical feedback!

There is also this video which talks about it:
Talking Cars: Tesla Model 3 Gets Brake Update and Recommendation

And the CR update:
Tesla Model 3 Gets CR Recommendation After Braking Update

In CR’s initial review of the Model 3, testers noted that the EV’s 152 feet to stop from 60 mph was 7 feet longer than a Ford F-150 pickup’s stopping distance, and 25 feet longer than Tesla’s own Model X SUV’s. In retesting after the software update was downloaded, the sedan stopped in 133 feet from 60 mph, an improvement of 19 feet.

The new shorter distance is typical for a compact luxury car and matches the 133 feet that Tesla claims its own testing found, using the same tires as those on our Model 3.

 

[Daniel in SD]

The 126 number wasn't from CR, it was Tesla's data with better tires. The first post on this thread:

I tested myself using a Vbox Sport and measured 125.62 and 122.66 in back to back stops with the stock 18" MXM4 tires.

 

[Nocturnal]

This is awesome actually, get all the bugs worked out so when, if, we can afford to buy a 3 (after the S is paid off)
It will be KICK A$$ PERFECT.

It's already the safest car on the planet. People unfairly set the bar far too high on Teslas.

 

[⚡️ELECTROMAN⚡️]

It's already the safest car on the planet. People unfairly set the bar far too high on Teslas.

Elon did say the Model S and Model X were slightly safer due to being bigger vehicles. Do you not believe him?

 

[Daniel in SD]

Elon did say the Model S and Model X were slightly safer due to being bigger vehicles. Do you not believe him?

54% of fatal accidents are single vehicle crashes. Extra mass wouldn't help much in those so it might be very close.
In the end it's very difficult to determine what the "safest" car is, there are too many variables and not a large enough sample size. There are many models of vehicle that have never had a single fatality.

 

[Nocturnal]

Elon did say the Model S and Model X were slightly safer due to being bigger vehicles. Do you not believe him?

All the charts I've seen from Tesla show the 3 as being safer. Large vehicles being "safer" is very much situational.