[srfilipek]

Tesla's page in question is quite clear about their methodology, and I can't really see the fault in it:

> The Vehicle Safety Score represents the “relative risk of injury with respect to a baseline of 15%,” according to NHTSA. Model 3 achieved a Vehicle Safety Score of 0.38, which is lower than any other vehicle rated in NHTSA’s public documents.

How can the NHTSA create a safety score regarding risk of injury, and then say that you can't use it to make a statement about the risk of injury?

[SiempreViernes]

AS explained by others, the NHTSA ratings are for one type of collision and valid within a weight class.

The methodology simply doesn't provide the data for making the type of global claims that Tesla make.

[Hypx]

It also ignores the way a car is being used. Sports cars are consistently more dangerous than say, minivans. This is true even if the minivan is poorly rated and the sports car is top-of-class in its safety rating.

[windexh8er]

Source?

A minivan has a higher center of gravity so in an example where a minivan is cornering aggressively, say to avoid a collision, the rollover likelihood is higher than that of a sports car. As I understand it safety ratings are generally after occupancy protection and aren't concerned with the class of vehicle which goes against what you've claimed.

From the NHTSA website [0]:

"Can I compare vehicles from different classes?

Side crash rating results can be compared across all classes because all vehicles are hit with the same force by the same moving barrier or pole.

Rollover ratings can also be compared across all classes. Frontal crash rating results can only be compared to other vehicles in the same class and whose weight is plus or minus 250 pounds of the vehicle being rated. This is because a frontal crash rating into a fixed barrier represents a crash between two vehicles of the same weight."

And again they are, generally, looking for impact to occupant, for example for the "Side Pole Crash Test Scenario" under "Test Details" they are looking at "Evaluation of injury to the head, chest, lower spine, abdomen, pelvis".

Just because a sports car is a different class of vehicle does not make it inherently less safe. The driver input can change that for any class of vehicle.

[0] https://www.nhtsa.gov/ratings

[dragontamer]

> Source?

A minivan weighs over 4500 lbs, while a sports car probably weighs 3000 lbs. In most collision situations, the heavier car is safer.

Frontal collision tests (and frontal overlap tests) are against stationary objects. So a minivan is tested with 4500+lbs of weight, while a sports car is only tested with 3000 lbs of weight.

Some tests are weight dependent. Others have a static weight.

-----------

I know some friends who survived getting hit by a bus. Riding in a 5000lb+ vehicle helps in these situations. There is a huge degree of safety that is afforded by just having a heavier vehicle.

[windexh8er]

While that's a great anecdote it's not a source. We could counter your argument by saying that the power to weight ratio of large vehicle is less than that of sports cars. Also because of softer suspensions not tuned for aggressive handling makes for vehicles that get into more crashes due to characteristics that make them worse with regard to stopping before a crash, unable to accelerate out of a compromising situation, or at at odds with a much higher likelihood of rollover due to aggressive maneuvering.

As an aside I have lots of friends who own fast cars who haven't gotten into accidents by avoiding them. Thankfully they were driving lighter vehicles.

I won't berate survivorship bias here.

[dragontamer]

> As an aside I have lots of friends who own fast cars who haven't gotten into accidents by avoiding them. Thankfully they were driving lighter vehicles.

And we all have friends who regularly avoid accidents in motorcycles. The difference is that you HAVE to avoid an accident to survive them, especially for motorcyclists (the extreme case of smallest but most agile vehicle). While if you're in a big car, you can have an accident and survive.

Its a very big difference. If you ever are a bit tired or distracted, the "trust my reactions to save me" technique will fail.

But if you're tired / distracted, but armored up in a 5000lb or 6000lb vehicle, you'll probably survive whatever hits you.

The survival rate of 18-wheelers (even when they're distracted and tired from driving 10+ hours a day) is quite high. Multi-ton armor just makes things safer.

[nullwasamistake]

He's right that heavy vehicles are statistically much safer across the board. If you search for list of cars with lowest accident fatality rate it's almost all giant trucks and SUV's.

You're heavier than the cars around you which helps a lot, but the extra weight also smashes through a lot of obstacles.

[lm28469]

> As an aside I have lots of friends who own fast cars who haven't gotten into accidents by avoiding them.

As in driving aggressively and avoiding accidents they were about to create ? Statistically most accidents are rear ends and side collisions, both of which you most likely won't see coming with enough time to react let alone move your car. And getting plowed by an SUV when you're sitting in a sport car means your head is on the absolute worst position you could think of.

Bikers say the same "I'm small, agile and fast, no accidents for me", yet they're disproportionally represented in crash stats.

[jjallen]

If we're actually talking about Tesla sports cars here, Model 3 weighs 20%-30% more than 3000 lbs. Model S weighs 4,700 lbs.

[lm28469]

Not sure about all the downvotes here, seems like big/heavy car = better. https://www.technologyreview.com/s/413018/laws-of-physics-pe...

[Retric]

Big has benefits for the occupants in terms of larger crumple zones etc, heavy does not. What’s important is jerk and acceleration not your final velocity.

Electric cars actually weigh more due to batteries, but that’s not particularly helpful.

[Cookingboy]

>Side crash rating results can be compared across all classes because all vehicles are hit with the same force by the same moving barrier or pole.

That is incorrect. Your statement is only true in the case of single vehicle inelastic collisions, which is the only type tests NHTSA conducts.

[windexh8er]

No, actually you are incorrect.

What I wrote is in quotes and directly taken from the NHTSA site. Those are not my words. Try taking a look at the site first.

[abstractbarista]

My reading comprehension is far from stellar, but I struggled to find any disingenuous statement that Tesla has made in this (specific) scenario.

1. NHTSA released data showing the Model 3 has the best score in their dataset.

2. Tesla happily publishes this to show off.

3. NHTSA gets grumpy.

4. (???)

[rtkwe]

> “the lowest probability of injury of all cars the safety agency has ever tested.”

NHTSA is taking issue with how the results are being framed. The ratings are only valid across classes in some cases and for stuff like front impact rating the numbers are only valid for cars with very similar weights, Tesla is using the numbers to say they have the lowest probability across all cars. See [0] page 7 for the original letter, the NHTSA has very specific guidelines for what their numbers actually mean and how they can't be compared in all cases across different vehicles, Tesla has violated those by comparing their score to all vehicles which definitely includes vehicles outside the +/- 250 lbs weight difference the NHTSA feels is appropriate.

[0] https://www.plainsite.org/documents/fnrhg/tesla-nhtsa-foia-r... (still reading but see bottom of page 3 and top of page 4 and the NHTSA letter on page 7)

edit: To expand having read more they specifically say that in a collision between vehicles of different classes the numbers become largely meaningless and that the larger vehicle like an SUV will have the lower probability of injury compared to the smaller vehicle.

[Someone]

Aside from the “you can’t compare those numbers across categories” issue, there’s the fact that Tesla makes the incorrect inference “safest per collision” ⇒ “lowest probability of injury of all cars”.

I’m not making any claim about Tesla’s cars (because of its low center of gravity and relatively large weight, they likely are quite a bit safer than the average car in collisions) but if brand B has distracting UI, bad steering, or whatever, that causes it to slam into walls twice as often as cars of brand C, being safer in a single collision may not offset that.

[mensetmanusman]

Lawyers from competitors don’t want govt. data used as advertising claims.

[dsfyu404ed]

>How can the NHTSA create a safety score regarding risk of injury, and then say that you can't use it to make a statement about the risk of injury?

Government is highly averse to saying or doing anything that could possibly come back to bite them (with exceptions beyond the scope of this comment) hence they will compile stats but are non-committal about drawing any conclusions from or interpreting those stats.

[rtkwe]

No it's not even that. The numbers they produce for front impact don't generalize across class and the real rule is basically the larger vehicle will have lower injury risk in mixed vehicle collisions.