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Tesla Model S achieves best safety rating of any car ever tested

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Re: Tesla Model S achieves best safety rating of any car ever tested

#61

Post by dredmorbius »

sbierwagen wrote: post #31

It helps that it weighs 4,600 pounds. (More than a thousand pounds heavier than the Volvo S60 they compare it to.) Heavier vehicles always do better-- which is why SUVs survive crashes so well.

First: SUVs don't survive crashes particularly well -- they're very prone to rollover, which generally makes for a bad day for the occupant. I've witnessed multiple large-SUV vs. Camry (mid-sized sedan) accidents where the Toyota fared far better (walk away vs. ambulance or worse).

Weight can be a factor, especially in multiple-vehicle accidents, where the heavier vehicle simply has more momentum and kinetic energy. In a multiple-vehicle accident, the larger vehicle experiences lower g-forces, and the occupants lower forces.

Collisions with a stationary object (the basis for the NHTSA tests) largely takes this factor out of the equation. More mass can _still_ result in better survivability if it means more material around the driver, but here the choice of materials and engineering matter far more. Look at the comparison tests of classic (1950s/1960s) and modern (post 1980 and more recent) vehicles:

http://www.youtube.com/watch?v=joMK1WZjP7g

I don't know the GVW of the Bel Aire, but I suspect it's rather higher than that of the Malibu.

Of course, modern vehicles with poor engineering and materials can also fare badly:

http://www.youtube.com/watch?v=g5SRyG6UR2A

Re: Tesla Model S achieves best safety rating of any car ever tested

#62

Post by notaddicted »

ISL wrote: post #36
Florin_Andrei wrote: post #29

Earlier quoted context omitted.

> There's winning and there's crushing the opponents. Crushing the opponents while your car remains uncrushed in the test (or the least crushed). That's what you get when you ask the rocket scientist to make you a car.

If you ask a rocket scientist to make you a car that passes the crash test ratings alone, they'll build you a tungsten dump truck. If you're going to win, you might as well reach the destination without noticing that you've had a collision.

I believe one of the tests is crashing into a wall that yields very little, so the tungsten dumptruck would fare poorly, exciting as it would be to drive.

EDIT: this one: http://youtu.be/V5R80yUUVNk

Re: Tesla Model S achieves best safety rating of any car ever tested

#63

Post by ra88it »

eru wrote: post #58
ra88it wrote: post #50

Elon Musk clearly writes these things himself. That, or he's got a bunch of other folks like him working at Tesla. Either way, it's exciting times. It's fun to be inspired by a company. To find something that keeps getting better as it unfolds...

Or they work together at creating them. I.e. he writes a draft, gets it fleshed out, and he applies some finishing touches.

Sure. I guess what I mean is I can see his hand in the work. (Or at least I've convinced myself of that.)

Tesla's PR is many things, but it's not safe. It feels plain and unadorned and yet genuinely enthusiastic and precisely bold.

I used to be worried that Musk's hand was too heavy on the tiller. Now I'm just enjoying the show.

Re: Tesla Model S achieves best safety rating of any car ever tested

#64

Post by D_Alex »

Okay, I am convinced this car is superb. How about we... build more of them? There is a Ford factory here in Australia that is due to be shut down in 2 years, it could be converted, and us Aussies would love to be able to buy this car. I personally promise to buy one if it is built here. The Aussie government might chip in as well.

Re: Tesla Model S achieves best safety rating of any car ever tested

#65

Post by mikeash »

akira2501 wrote: post #60
mikeash wrote: post #41

Earlier quoted context omitted.

How much does the gas tank, motor, radiator, transmission, etc. in a normal car weigh? Have to subtract that out of the 1,200lbs to see how much extra is added.

Mid-Range Estimates: Engine: 300 to 450 pounds Transmission: 120 to 140 pounds Gas Tank: 20 to 25 pounds Radiator: 20 to 30 pounds So, roughly 460 to 645 pounds. Add 110 pounds for 15 gallons of gas. The comparison is a little more difficult than this though, because the batteries just store energy. The Model S still has a (416hp) motor, there are a few other differences (regenerative vs standard brakes) and equivale…

Yep, it gets a bit tough, but that 460-645lbs range seems like a decent stab at it. I don't get the impression that the Model S's motors are all that heavy compared to the rest of this stuff, but I could be wrong. I'd also wager that the Model S needs a full set of mechanical brakes for emergency purposes, since it still needs to be able to stop safely even if all the electronics suddenly quit while going down the highway at 70MPH. And then there's the question of whether you compare against a 416hp motor, or a less powerful gas motor that would be more typical for a car that size....

Re: Tesla Model S achieves best safety rating of any car ever tested

#66

Post by eru »

ra88it wrote: post #63
eru wrote: post #58

Earlier quoted context omitted.

Or they work together at creating them. I.e. he writes a draft, gets it fleshed out, and he applies some finishing touches.

Sure. I guess what I mean is I can see his hand in the work. (Or at least I've convinced myself of that.) Tesla's PR is many things, but it's not safe. It feels plain and unadorned and yet genuinely enthusiastic and precisely bold. I used to be worried that Musk's hand was too heavy on the tiller. Now I'm just enjoying the show.

> Tesla's PR is many things, but it's not safe. It feels plain and unadorned and yet genuinely enthusiastic and precisely bold.

In most big companies the PR people have to cover their asses, but don't have too much ownership of what they say. Whereas for Tesla someone who's not afraid is calling the shots.

Re: Tesla Model S achieves best safety rating of any car ever tested

#67

Post by mrb »

sbierwagen wrote: post #31

It helps that it weighs 4,600 pounds. (More than a thousand pounds heavier than the Volvo S60 they compare it to.) Heavier vehicles always do better-- which is why SUVs survive crashes so well.

"Heavier vehicles always do better"

You are wrong. At least in the perspective of crash tests.

In a crash test against a wall (equal amount of kinetic energy transferred to the wall and to the vehicle), a lightweight vehicle does better than an otherwise identical but heavier vehicle. This is because its mass is less, therefore there is less kinetic energy to dissipate.

However in road crashes, heavy vehicles fare better because the heavy vehicle transfers more kinetic energy to the more lightweight vehicle.

NHTSA crash ratings are well known to not reflect this difference. But the point remain that heavy vehicles are disadvantaged compared to lightweight vehicle, and the fact the Model S does so well despite its weight is a testament to its good crash resistance.

Re: Tesla Model S achieves best safety rating of any car ever tested

#68

Post by corresation »

sbierwagen wrote: post #57
corresation wrote: post #43

Earlier quoted context omitted.

What is the calculated correlation between NHTSA vehicle safety score and vehicle weight. I don't know this, but suspect that it is a less significant factor than you imply. Add that the Tesla is 1000lbs+ of battery. Safety is engineering and materials. More materials help, of course, but more materials without the engineering simply equals more kinetic energy. There are vehicles from big SUVs to tiny SMART cars doin…

Amusing that you mention the Smart Fortwo. http://www.iihs.org/news/rss/pr041409.html ARLINGTON, VA — Three front-to-front crash tests, each involving a microcar or minicar into a midsize model from the same manufacturer, show how extra vehicle size and weight enhance occupant protection in collisions. These Insurance Institute for Highway Safety tests are about the physics of car crashes, which dictate that very sma…

But all things being equal

Rater irrational requirement, given that we're talking about engineering. It short circuits the entire conversation.

In any case, I find it odd that you find my reference of the Smart "humorous". While the IIHS held their results as demonstrating bigger versus smaller, in actual reality it primarily demonstrated more expensive versus less expensive -- there is no great confusion that less expensive cars often sacrificed safety, and this was true at all vehicle sizes (e.g. some early budget Kia minivans and SUVs were deathtraps). It seems to have mostly passed now that even economical cars like the Cruze are posting stellar results.

But let's assume that a greater weight, by itself, equals better safety. So would that Volvo do better than the Tesla if they filled the trunk full of concrete blocks?

Note that I didn't say that weight doesn't correlate with safety, but that it doesn't correlate nearly as strongly as you seem to imply -- e.g. saying that a large sedan is 1000lbs heavier than another large sedan in no way, I would guess, leads to a conclusion that it will also do better in safety tests.

Re: Tesla Model S achieves best safety rating of any car ever tested

#70

Post by akira2501 »

mikeash wrote: post #65
akira2501 wrote: post #60

Earlier quoted context omitted.

Mid-Range Estimates: Engine: 300 to 450 pounds Transmission: 120 to 140 pounds Gas Tank: 20 to 25 pounds Radiator: 20 to 30 pounds So, roughly 460 to 645 pounds. Add 110 pounds for 15 gallons of gas. The comparison is a little more difficult than this though, because the batteries just store energy. The Model S still has a (416hp) motor, there are a few other differences (regenerative vs standard brakes) and equivale…

Yep, it gets a bit tough, but that 460-645lbs range seems like a decent stab at it. I don't get the impression that the Model S's motors are all that heavy compared to the rest of this stuff, but I could be wrong. I'd also wager that the Model S needs a full set of mechanical brakes for emergency purposes, since it still needs to be able to stop safely even if all the electronics suddenly quit while going down the hi…

A Chevy 383 can make about 400hp+ in about 620 pounds. If we choose all our numbers for comparable cars that are highly in favor of the Tesla, we're still only likely going to match the weight of the Tesla's battery pack alone.

The Model S curb weight is 4,647 pounds. A Cadillac STS, which is 5" narrower but very nearly the same in every other dimension as the Model S is only 3,922 pounds. That leaves the Model S 725 pounds heavier, still quite a bit of difference.

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