Author Topic: Subcompacts fare poorly in new crash test  (Read 11530 times)

the fixer

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Subcompacts fare poorly in new crash test
« on: January 22, 2014, 03:27:50 PM »
I thought this was interesting. It's good to remember that the government crash tests are not always the most complete.

http://www.boston.com/business/news/2014/01/22/subcompact-cars-fare-poorly-new-crash-tests/lXWXEPAbEAlUt7Btr9p5nM/story.html

I'll preempt the discussion by pointing out that this is only showing that subcompacts are less safe in frontal offset collisions, not in other areas. If you believe yourself to be a safe driver, you shouldn't be as concerned with front impact data as with areas like side impacts. Plus, if you know your car is not the safest in the world, it's all the more reason to drive it conservatively and internalize that risk. Just imagine there's a metal spike coming out of the steering column.

http://www.mrmoneymustache.com/2012/06/07/safety-is-an-expensive-illusion/

MooseOutFront

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Re: Subcompacts fare poorly in new crash test
« Reply #1 on: January 22, 2014, 03:34:10 PM »
Yes I read that recently when I tried and failed to refute a friend's claim that a minivan was safer.  I think I also recall that the linked test did these collisions at 70 mph which isn't a very realistic speed for a head-on based on accident statistics, but I don't remember exactly where I saw that.

Either way I'm having a bit of a hard time wrapping my head around getting a prius like I want to while I have an infant and a toddler in car seats.

Spork

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Re: Subcompacts fare poorly in new crash test
« Reply #2 on: January 22, 2014, 03:41:09 PM »
Yes I read that recently when I tried and failed to refute a friend's claim that a minivan was safer.  I think I also recall that the linked test did these collisions at 70 mph which isn't a very realistic speed for a head-on based on accident statistics, but I don't remember exactly where I saw that.

I would think (warning: I'm guessing) that 70 mph is not a realistic speed -- that it is far, far too low.  A realistic speed for a head on with both cars doing 55mph would be 110mph. 

Possibly if you add in "one or both cars is likely to hit the brakes" ... maybe 70 is reasonable.  It still seems low.

MooseOutFront

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Re: Subcompacts fare poorly in new crash test
« Reply #3 on: January 22, 2014, 03:55:02 PM »
What I saw said the speeds they used for this test were too fast and would be relevant to like only .04% of real world head on collisions which occur at slower speeds.  But here I am again being lazy and not going and looking up my source for this so take it as hearsay.

the fixer

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Re: Subcompacts fare poorly in new crash test
« Reply #4 on: January 22, 2014, 03:59:15 PM »
Actual stats from the article:

Insurance industry spokesman says in the video that 10k people per year die in front collision crashes, and they estimate that 25% of those crashes involve some overlap (not a full head-on, only part of the front of the vehicle takes the hit)

In the small overlap test, 25 percent of the vehicle's front end on the driver's side strikes a rigid barrier at 40 MPH. The government crash test has the entire car strike a rigid barrier at 35 MPH.

cbgg

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Re: Subcompacts fare poorly in new crash test
« Reply #5 on: January 22, 2014, 04:30:16 PM »
I drive a subcompact (Yaris) and from a non-scientific point of view - there is no WAY I'm safer in that thing that I would be in a larger vehicle with the same features.  That knowledge certainly effects my behavior and encourages me to drive more safely.  Since I do mostly city driving I feel ok about it...but do worry about getting T-boned.

When I  move to the Bay Area and 80 MPH driving on crazy crowded freeways becomes part of my reality, I'll likely move up in size from compact to sub-compact.  It bums me out because I really enjoy my tiny little Yaris.  It's a dream to park, wonderful on gas, and very comfy and well built. 

While sub-compacts are not "the safest" cars on the road it's not like they are irresponsibly unsafe.  I'd probably feel differently if I had kids. 

The best outcome for us all would be if fewer and fewer drivers choose the big cars and trucks that can cause such devastating damage to drivers, pedestrians, cyclists, and other road users.  And of course, if more people chose to walk/bike/take public transit/commute shorter distances/etc.


ThisIsBananas

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Re: Subcompacts fare poorly in new crash test
« Reply #6 on: January 22, 2014, 04:45:22 PM »

I would think (warning: I'm guessing) that 70 mph is not a realistic speed -- that it is far, far too low.  A realistic speed for a head on with both cars doing 55mph would be 110mph. 

Possibly if you add in "one or both cars is likely to hit the brakes" ... maybe 70 is reasonable.  It still seems low.

Two cars colliding at 55mph is not the same as a car hitting another at 110, its equivalent to a car hitting another at 55mph.  That's a pretty common misconception.

Spork

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Re: Subcompacts fare poorly in new crash test
« Reply #7 on: January 22, 2014, 04:56:09 PM »

I would think (warning: I'm guessing) that 70 mph is not a realistic speed -- that it is far, far too low.  A realistic speed for a head on with both cars doing 55mph would be 110mph. 

Possibly if you add in "one or both cars is likely to hit the brakes" ... maybe 70 is reasonable.  It still seems low.

Two cars colliding at 55mph is not the same as a car hitting another at 110, its equivalent to a car hitting another at 55mph.  That's a pretty common misconception.

Color me surprised.  I googled and quickly got explanations that were either (1) above my head, (2) used equations I haven't seen in 30 years or (3) both.

GuitarStv

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Re: Subcompacts fare poorly in new crash test
« Reply #8 on: January 23, 2014, 06:18:06 AM »

I would think (warning: I'm guessing) that 70 mph is not a realistic speed -- that it is far, far too low.  A realistic speed for a head on with both cars doing 55mph would be 110mph. 

Possibly if you add in "one or both cars is likely to hit the brakes" ... maybe 70 is reasonable.  It still seems low.

Two cars colliding at 55mph is not the same as a car hitting another at 110, its equivalent to a car hitting another at 55mph.  That's a pretty common misconception.

Well, it depends on the angle right?  Head on, two cars going 55 will add vectors straight up.  A T accident they'll be at 90 degrees to each other so net momentum shouldn't exceed 55 in any direction.

aclarridge

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Re: Subcompacts fare poorly in new crash test
« Reply #9 on: January 23, 2014, 07:31:03 AM »
Yeah Bananas I'm not sure what you're saying. A head-on collision between 2 cars going 55 each is the same thing as a car going 110 hitting a car that's stationary. Isn't it? Am I crazy?

acroy

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Re: Subcompacts fare poorly in new crash test
« Reply #10 on: January 23, 2014, 07:43:33 AM »
head-on at 55 to 70 - you're likely to die. Try not to do it! But I don't know how much of a difference a bigger car would really make. I have an uncle nearly killed when a tire came through the windshield of his Suburban at 80mph. 6" to the left and it would have taken him out. At those relative speeds, physics hurts.

PantsOnFire

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Re: Subcompacts fare poorly in new crash test
« Reply #11 on: January 23, 2014, 09:21:36 AM »
I thought the consensus around here was that you're supposed to think about the other guy, not yourself or your family.  Get in your Metro and hope that you only end up colliding with cars over 7,000 lbs GVW so those other people are safe.  It's the right thing to do.  And think about how much money you'll save when your whole family is dead and no longer needs housing, food, etc. 

Emilyngh

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Re: Subcompacts fare poorly in new crash test
« Reply #12 on: January 23, 2014, 09:32:33 AM »
Damage to the car will depend on how much of the original kinetic energy of the car is absorbed by the car (and how its structure reacts to this energy) vs how much is transformed into other energy.  Kinetic energy equals 1/2 times the object's mass, times it's velocity squared.

So, if you have a car moving at 55 mph hit another car head-on moving at 55mph and both cars stop moving completely as a result of the crash, each would absorb its own initial kinetic energy as damage (which would be just dependent on its mass and initial velocity of 55 mph).

If you have a car hit a brick wall at 55 mph and is completely stopped by the wall, it would absorb its initial kinetic energy and have the exact same damage as the cars hitting head-on. (This is assuming that the brick wall is so sturdy that it does not absorb any of the energy during the crash).

If you have a car moving at 55 mph hit a brick wall and bounce off of it with all of the kinetic energy transformed into it bouncing backwards, then there would be no damage to the car at all.

If you have a car moving at 55 mph hit a stationary car, which then bounces off of it, with the first car transferring all of its kinetic energy into the kinetic energy of the second car, there will be no damage to either car. (completely elastic collision)

If you have a car moving at 55 mph hit a stationary car and the stationary car bounces off of it and the original car bounces back some too, there will be less damage to the original car than if it hit a brick wall.

Etc, etc. 


« Last Edit: January 23, 2014, 09:39:45 AM by Emilyngh »

Iron Mike Sharpe

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Re: Subcompacts fare poorly in new crash test
« Reply #13 on: January 23, 2014, 11:23:59 AM »
How often do people hit other cars head-on at 55+?  Seems very rare to me.  Seems like you'd have to be driving the wrong way down a highway.

I'll keep my sub-compact and the huge savings I get with it.

somepissedoffman

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Re: Subcompacts fare poorly in new crash test
« Reply #14 on: January 23, 2014, 11:58:22 AM »
Yeah Bananas I'm not sure what you're saying. A head-on collision between 2 cars going 55 each is the same thing as a car going 110 hitting a car that's stationary. Isn't it? Am I crazy?
Mostly a function of the energy in the system.  A car going 55mph has a certain amount of kinetic energy ((1/2)*m*V^2).  If Car #2 also is doing 55, there's twice as much energy in the system (double the mass of stuff doing 55).  If Car #1 is doing 110, and Car #2 is stationary, there's 4x more energy in the system because of that whole V squared nonsense.

And that energy is going to go somewhere, as Emilyngh describes, in the most unpleasant of ways.

Jamesqf

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Re: Subcompacts fare poorly in new crash test
« Reply #15 on: January 23, 2014, 12:08:02 PM »
The problem with this testing is that it assumes the crash has happened, and doesn't account for crashes that don't happen because the cars are small enough to miss each other.

It's also worth noting that the tests were done by insurance companies, whose profits & job security depend on scaring the public into buying their products.

Spork

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Re: Subcompacts fare poorly in new crash test
« Reply #16 on: January 23, 2014, 12:20:18 PM »
How often do people hit other cars head-on at 55+?  Seems very rare to me.  Seems like you'd have to be driving the wrong way down a highway.

I'll keep my sub-compact and the huge savings I get with it.

Not all highways are divided.  We've got a ton of them around here that are 70mph each way.  I have no idea how common it is, but it does happen.  I'd guess usually due to a cell phone or a drunk.

randymarsh

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Re: Subcompacts fare poorly in new crash test
« Reply #17 on: January 23, 2014, 12:42:15 PM »
I thought the consensus around here was that you're supposed to think about the other guy, not yourself or your family.  Get in your Metro and hope that you only end up colliding with cars over 7,000 lbs GVW so those other people are safe.  It's the right thing to do.  And think about how much money you'll save when your whole family is dead and no longer needs housing, food, etc.

There's a spectrum. I agree that driving the smallest car possible will put you at a disadvantage in the event of a crash. But that doesn't mean we should all be driving Hummers. If you don't think a Yaris provides enough protection, maybe look at a an Accord. Perhaps a Forester or CRV. But don't jump all the way to a Suburban just for safety.


luigi49

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Re: Subcompacts fare poorly in new crash test
« Reply #18 on: January 23, 2014, 02:21:10 PM »
Just use defensive driving.  Let the suv rule the street.   Like this 2 guys  trying to find out who has a better SUV

http://www.komonews.com/news/local/Road-rage-drivers-collide-multiple-times-crash-on-I-90-240505491.html

frugalman

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Re: Subcompacts fare poorly in new crash test
« Reply #19 on: January 23, 2014, 02:30:06 PM »
I drive a sub compact Honda Fit. I drive in the right lane, at the speed limit. I'm always aware of cars and traffic. I've made up my mind that in the event of an impending collision, I'm going to yank the wheel hard right and take my chances in the corn field or whatever is on the right. It's good to have a plan. I fully realize stuff can happen so quickly, I wouldn't have time to yank the wheel. I try not to get myself in that position, by leaving a good gap to the car in front of me.

Posthumane

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Re: Subcompacts fare poorly in new crash test
« Reply #20 on: January 23, 2014, 02:55:44 PM »
Yeah Bananas I'm not sure what you're saying. A head-on collision between 2 cars going 55 each is the same thing as a car going 110 hitting a car that's stationary. Isn't it? Am I crazy?
Mostly a function of the energy in the system.  A car going 55mph has a certain amount of kinetic energy ((1/2)*m*V^2).  If Car #2 also is doing 55, there's twice as much energy in the system (double the mass of stuff doing 55).  If Car #1 is doing 110, and Car #2 is stationary, there's 4x more energy in the system because of that whole V squared nonsense.

And that energy is going to go somewhere, as Emilyngh describes, in the most unpleasant of ways.
Mmm, not exactly. Whether you have two cars closing on each other, each with a speed of X, or one stationary car and another car going with a speed of 2X, the results are the same. Their velocity in relation to the ground doesn't matter, since it is not the ground that they are hitting, only their velocity in relation to each other. Imagine two objects colliding in space, with no ground supporting them. Is one staionary and the other moving, or are they both moving towards each other at half the speed? Depends on your frame of reference.

Spork

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Re: Subcompacts fare poorly in new crash test
« Reply #21 on: January 23, 2014, 03:31:41 PM »
Yeah Bananas I'm not sure what you're saying. A head-on collision between 2 cars going 55 each is the same thing as a car going 110 hitting a car that's stationary. Isn't it? Am I crazy?
Mostly a function of the energy in the system.  A car going 55mph has a certain amount of kinetic energy ((1/2)*m*V^2).  If Car #2 also is doing 55, there's twice as much energy in the system (double the mass of stuff doing 55).  If Car #1 is doing 110, and Car #2 is stationary, there's 4x more energy in the system because of that whole V squared nonsense.

And that energy is going to go somewhere, as Emilyngh describes, in the most unpleasant of ways.
Mmm, not exactly. Whether you have two cars closing on each other, each with a speed of X, or one stationary car and another car going with a speed of 2X, the results are the same. Their velocity in relation to the ground doesn't matter, since it is not the ground that they are hitting, only their velocity in relation to each other. Imagine two objects colliding in space, with no ground supporting them. Is one staionary and the other moving, or are they both moving towards each other at half the speed? Depends on your frame of reference.

I was skeptical too.  I googled.  I appear to be wrong.  It looks like there is even a Mythbusters episode on it where they test it -- and they, too, are surprised.

55 mph vs wall tested the same as 2 cars doing 55 mph and closing.  It tested totally differently than 110mph vs wall.

the fixer

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Re: Subcompacts fare poorly in new crash test
« Reply #22 on: January 23, 2014, 03:39:45 PM »
How often do people hit other cars head-on at 55+?  Seems very rare to me.  Seems like you'd have to be driving the wrong way down a highway.

I'll keep my sub-compact and the huge savings I get with it.
It's not that common, but not that rare either, mostly on two-lane country roads.

Maybe not the most up-to-date source, but a quick Google found http://advance.uconn.edu/2006/060327/06032707.htm "In 2003, head-on collisions on American roads accounted for 10 percent of traffic deaths, a recent study shows."

econberkeley

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Re: Subcompacts fare poorly in new crash test
« Reply #23 on: January 23, 2014, 03:56:30 PM »
Numerous people told me that they mainly bought the big size suv to be safer not for its big interior space. People gets into debt in order to be safe. Interesting concept indeed.

Wanderer

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Re: Subcompacts fare poorly in new crash test
« Reply #24 on: January 23, 2014, 03:58:44 PM »
Yeah Bananas I'm not sure what you're saying. A head-on collision between 2 cars going 55 each is the same thing as a car going 110 hitting a car that's stationary. Isn't it? Am I crazy?
Mostly a function of the energy in the system.  A car going 55mph has a certain amount of kinetic energy ((1/2)*m*V^2).  If Car #2 also is doing 55, there's twice as much energy in the system (double the mass of stuff doing 55).  If Car #1 is doing 110, and Car #2 is stationary, there's 4x more energy in the system because of that whole V squared nonsense.

And that energy is going to go somewhere, as Emilyngh describes, in the most unpleasant of ways.
Mmm, not exactly. Whether you have two cars closing on each other, each with a speed of X, or one stationary car and another car going with a speed of 2X, the results are the same. Their velocity in relation to the ground doesn't matter, since it is not the ground that they are hitting, only their velocity in relation to each other. Imagine two objects colliding in space, with no ground supporting them. Is one staionary and the other moving, or are they both moving towards each other at half the speed? Depends on your frame of reference.

I was skeptical too.  I googled.  I appear to be wrong.  It looks like there is even a Mythbusters episode on it where they test it -- and they, too, are surprised.

55 mph vs wall tested the same as 2 cars doing 55 mph and closing.  It tested totally differently than 110mph vs wall.

Semi-sorta-maybe-not really.  If we suppose cars do not deform at all upon colliding with something, it's totally the same thing to run into another car going 55 headlong at 55 or to run into a concrete wall at 110 mph.  In reality, though, cars have crumple zones built in.  Walls don't, they deform much less than cars.  So a car slamming into a wall at 110 mph is going to deform a lot, while a car slamming into another deformable car is going to deform less since the other car is undergoing its share of deformation.  Still not something you want to try, though. 

Note that a frickin' huge SUV slamming into a subcompact is not going to deform as much as a frickin' huge SUV slamming into another frickin' huge SUV.  Hitting a SUV head-on in a subcompact leans towards the "driving into a wall at 110 mph" end of the spectrum. 

LauraG

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Re: Subcompacts fare poorly in new crash test
« Reply #25 on: January 23, 2014, 05:35:11 PM »
Actual stats from the article:

Insurance industry spokesman says in the video that 10k people per year die in front collision crashes, and they estimate that 25% of those crashes involve some overlap (not a full head-on, only part of the front of the vehicle takes the hit)

In the small overlap test, 25 percent of the vehicle's front end on the driver's side strikes a rigid barrier at 40 MPH. The government crash test has the entire car strike a rigid barrier at 35 MPH.

So, that's just over 3 people per 100,000 killed in front-end collisions and less than 1 in 100,000 killed in partial overlap collisions. Not something I'm going to lose sleep over (particularly because I do very little country highway or suburban "stroad" driving).

Spork

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Re: Subcompacts fare poorly in new crash test
« Reply #26 on: January 23, 2014, 05:37:46 PM »
Yeah Bananas I'm not sure what you're saying. A head-on collision between 2 cars going 55 each is the same thing as a car going 110 hitting a car that's stationary. Isn't it? Am I crazy?
Mostly a function of the energy in the system.  A car going 55mph has a certain amount of kinetic energy ((1/2)*m*V^2).  If Car #2 also is doing 55, there's twice as much energy in the system (double the mass of stuff doing 55).  If Car #1 is doing 110, and Car #2 is stationary, there's 4x more energy in the system because of that whole V squared nonsense.

And that energy is going to go somewhere, as Emilyngh describes, in the most unpleasant of ways.
Mmm, not exactly. Whether you have two cars closing on each other, each with a speed of X, or one stationary car and another car going with a speed of 2X, the results are the same. Their velocity in relation to the ground doesn't matter, since it is not the ground that they are hitting, only their velocity in relation to each other. Imagine two objects colliding in space, with no ground supporting them. Is one staionary and the other moving, or are they both moving towards each other at half the speed? Depends on your frame of reference.

I was skeptical too.  I googled.  I appear to be wrong.  It looks like there is even a Mythbusters episode on it where they test it -- and they, too, are surprised.

55 mph vs wall tested the same as 2 cars doing 55 mph and closing.  It tested totally differently than 110mph vs wall.

Semi-sorta-maybe-not really.  If we suppose cars do not deform at all upon colliding with something, it's totally the same thing to run into another car going 55 headlong at 55 or to run into a concrete wall at 110 mph.  In reality, though, cars have crumple zones built in.  Walls don't, they deform much less than cars.  So a car slamming into a wall at 110 mph is going to deform a lot, while a car slamming into another deformable car is going to deform less since the other car is undergoing its share of deformation.  Still not something you want to try, though. 

Note that a frickin' huge SUV slamming into a subcompact is not going to deform as much as a frickin' huge SUV slamming into another frickin' huge SUV.  Hitting a SUV head-on in a subcompact leans towards the "driving into a wall at 110 mph" end of the spectrum.

So... that's exactly what I would have said.  I hate to say a fun semi-sciencey TV program changed my mind, but it did.  It is really hard to argue with empirical evidence -- though I know they did one test, not 1000.

lr

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Re: Subcompacts fare poorly in new crash test
« Reply #27 on: January 23, 2014, 05:49:05 PM »
The tiniest car on the road was one of the safest, though.  http://www.iihs.org/iihs/ratings/vehicle/v/smart/fortwo

lr

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Re: Subcompacts fare poorly in new crash test
« Reply #28 on: January 23, 2014, 05:57:13 PM »
Oh, this is a new test that the Smart hasn't done, assuming it can.

Emilyngh

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Re: Subcompacts fare poorly in new crash test
« Reply #29 on: January 23, 2014, 06:56:09 PM »
Their velocity in relation to the ground doesn't matter, since it is not the ground that they are hitting, only their velocity in relation to each other. Imagine two objects colliding in space, with no ground supporting them. Is one staionary and the other moving, or are they both moving towards each other at half the speed? Depends on your frame of reference.

Actually, their velocity relative to the ground is what matters.   Or their velocity relative to any other single reference point, if you'd prefer to think of them in outerspace, is what matters.   If you want to make the reference point one of the cars even instead, fine, then that car is going 0 mph relative to itself.   That's the thing about relativity, you have to choose one frame; you can't make the reference point one car and somehow also the other car at the same time.

Like I said before, IMO the easiest way to think of it is in terms of kinetic energy.    While two moving cars have twice the kinetic energy of one moving car, that kinetic energy is transformed into the wreck of two cars, instead of one.

« Last Edit: January 23, 2014, 08:12:07 PM by Emilyngh »

Jamesqf

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Re: Subcompacts fare poorly in new crash test
« Reply #30 on: January 23, 2014, 09:54:47 PM »
Numerous people told me that they mainly bought the big size suv to be safer not for its big interior space. People gets into debt in order to be safe. Interesting concept indeed.

And for more interesting insights into human nature, they then fill the big 'safe' SUV with all sorts of distracting electronics, yak & text on their cell phones, drive at high speeds in snow & ice because 'it's got AWD, you know", and generally drive like invulnerable assholes.  All of which adds up to making them (and the rest of us) less safe than if they'd bought the crash test rating of zero subcompact.
« Last Edit: January 24, 2014, 11:08:27 AM by Jamesqf »

Iron Mike Sharpe

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Re: Subcompacts fare poorly in new crash test
« Reply #31 on: January 24, 2014, 08:43:46 AM »
The majority of the time I notice unsafe driving it's a soccer mom talking on the phone while driving an SUV.  I think it should be legal to shoot people who use the phone and drive.

jba302

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Re: Subcompacts fare poorly in new crash test
« Reply #32 on: January 24, 2014, 08:59:48 AM »
And for more interesting insights into human nature, they then fill the big 'safe' SUV with all sorts of distracting electronics, yak & text on their cell phones, drive at high speeds in snow & ice because 'it's got AWD, you know", and generally drive like invulnerable assholes.  All of which adds up to making them (and the rest of us) less safe than if they'd bought the creash test rating of zero subcompact.

Came in to make this point, leaving satisfied.

Posthumane

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Re: Subcompacts fare poorly in new crash test
« Reply #33 on: January 24, 2014, 09:27:07 AM »


Actually, their velocity relative to the ground is what matters.   Or their velocity relative to any other single reference point, if you'd prefer to think of them in outerspace, is what matters.   If you want to make the reference point one of the cars even instead, fine, then that car is going 0 mph relative to itself.   That's the thing about relativity, you have to choose one frame; you can't make the reference point one car and somehow also the other car at the same time.

Like I said before, IMO the easiest way to think of it is in terms of kinetic energy.    While two moving cars have twice the kinetic energy of one moving car, that kinetic energy is transformed into the wreck of two cars, instead of one.
Nope, the kinetic energy change is the same in both types of impact. What I'm saying is that two cars colliding head on at 55mph each is the same as one car at 110, and one car at 0. It is NOT the same as a car running into a non-movable wall at 110, but it is the same as a car running into a non-movable wall at 55.

If you want to solve it in terms of kinetic energy with reference to a stationary point on the ground, yes the car doing 110 has four times the kinetic energy as a car doing 55, and therefore twice the kinetic energy as two cars doing 55. However, only half of that energy is dissipated in a collision between the car going 110 and the car going 0 because the end result in a completely inelastic collision is that both cars end up going 55 in relation to the ground, stuck together.

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Re: Subcompacts fare poorly in new crash test
« Reply #34 on: January 24, 2014, 09:32:37 AM »
And for more interesting insights into human nature, they then fill the big 'safe' SUV with all sorts of distracting electronics, yak & text on their cell phones, drive at high speeds in snow & ice because 'it's got AWD, you know", and generally drive like invulnerable assholes.  All of which adds up to making them (and the rest of us) less safe than if they'd bought the creash test rating of zero subcompact.

Came in to make this point, leaving satisfied.

While there is some truth to this point, I've also noticed that assholes come in pretty much every package imaginable.   It doesn't matter if you're texting on the latest and greatest iPhone 17+ or a crappy Motorola flip phone from 2005. 

Posthumane

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Re: Subcompacts fare poorly in new crash test
« Reply #35 on: January 24, 2014, 09:34:15 AM »
Mmm, not exactly. Whether you have two cars closing on each other, each with a speed of X, or one stationary car and another car going with a speed of 2X, the results are the same. Their velocity in relation to the ground doesn't matter, since it is not the ground that they are hitting, only their velocity in relation to each other. Imagine two objects colliding in space, with no ground supporting them. Is one staionary and the other moving, or are they both moving towards each other at half the speed? Depends on your frame of reference.

I was skeptical too.  I googled.  I appear to be wrong.  It looks like there is even a Mythbusters episode on it where they test it -- and they, too, are surprised.

55 mph vs wall tested the same as 2 cars doing 55 mph and closing.  It tested totally differently than 110mph vs wall.
We are talking about two different things. I was saying that a car hitting a stationary car at 110 is the same as two cars at 55. It is definitely not the same as hitting an immovable wall at 110. The difference is that hitting another car with equal mass will result in the stationary car moving, whereas the wall will not.

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Re: Subcompacts fare poorly in new crash test
« Reply #36 on: January 24, 2014, 09:42:32 AM »
Mmm, not exactly. Whether you have two cars closing on each other, each with a speed of X, or one stationary car and another car going with a speed of 2X, the results are the same. Their velocity in relation to the ground doesn't matter, since it is not the ground that they are hitting, only their velocity in relation to each other. Imagine two objects colliding in space, with no ground supporting them. Is one staionary and the other moving, or are they both moving towards each other at half the speed? Depends on your frame of reference.

I was skeptical too.  I googled.  I appear to be wrong.  It looks like there is even a Mythbusters episode on it where they test it -- and they, too, are surprised.

55 mph vs wall tested the same as 2 cars doing 55 mph and closing.  It tested totally differently than 110mph vs wall.
We are talking about two different things. I was saying that a car hitting a stationary car at 110 is the same as two cars at 55. It is definitely not the same as hitting an immovable wall at 110. The difference is that hitting another car with equal mass will result in the stationary car moving, whereas the wall will not.

No, we're talking about the same thing.   
"car@55 vs wall" was roughly the same as "2 cars@55 head on" in their crash tests. 


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Re: Subcompacts fare poorly in new crash test
« Reply #37 on: January 24, 2014, 09:46:20 AM »
Yes, I just agreed with you. Two cars head on at 55 = one car hitting wall at 55 = one car at 110 hitting a car at 0. The first and third terms are what I was talking about in my original post, but some people confused that with the second term (the hitting the wall one).

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Re: Subcompacts fare poorly in new crash test
« Reply #38 on: January 24, 2014, 09:46:39 AM »
While there is some truth to this point, I've also noticed that assholes come in pretty much every package imaginable.   It doesn't matter if you're texting on the latest and greatest iPhone 17+ or a crappy Motorola flip phone from 2005.

I can honestly say I've never seen one of the original VW bug's being driven in an asshole sort of way. Probably because death is much closer than when soccer mom/dad is driving their Ford Land Titanic down the middle of 2 lanes trying to cue up a disney flick in the background. I know you are right that assholes come in all shapes and sizes, but the collateral damage potential between the two is much different as well.

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Re: Subcompacts fare poorly in new crash test
« Reply #39 on: January 24, 2014, 09:59:45 AM »
Yes, I just agreed with you. Two cars head on at 55 = one car hitting wall at 55 = one car at 110 hitting a car at 0. The first and third terms are what I was talking about in my original post, but some people confused that with the second term (the hitting the wall one).

oops, sorry.  My comprehension must be requiring another cup of coffee.


Side note: I have actually done my own personal experiments with driving a car into a concrete wall at 70mph.  Not recommended.

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Re: Subcompacts fare poorly in new crash test
« Reply #40 on: January 24, 2014, 10:09:18 AM »
Side note: I have actually done my own personal experiments with driving a car into a concrete wall at 70mph.  Not recommended.
Did you calculate the elasticity of the wall from the bounce-back? Because then I would really be impressed.

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Re: Subcompacts fare poorly in new crash test
« Reply #41 on: January 24, 2014, 10:33:31 AM »

Nope, the kinetic energy change is the same in both types of impact. What I'm saying is that two cars colliding head on at 55mph each is the same as one car at 110, and one car at 0. It is NOT the same as a car running into a non-movable wall at 110, but it is the same as a car running into a non-movable wall at 55.

If you want to solve it in terms of kinetic energy with reference to a stationary point on the ground, yes the car doing 110 has four times the kinetic energy as a car doing 55, and therefore twice the kinetic energy as two cars doing 55. However, only half of that energy is dissipated in a collision between the car going 110 and the car going 0 because the end result in a completely inelastic collision is that both cars end up going 55 in relation to the ground, stuck together.

I agree with all of the above, so I think there's just confusion in describing and responding to imaginary situations, especially with consideration to what happens after the cars collide.   For example, if a car going 110 hits a stationary car and the stationary car does not move (is somehow stuck), then the change in kinetic energy is going to be greater than two cars going 55 hitting head-on.   I use the stuck car example vs the wall, because some were saying earlier that the difference is just due to two cars absorbing the energy vs one.   However, I agree, that if the second car is free to move and winds up getting pushed along going 55 by the first car that was originally going 110, then the change in kinetic energy is comparable to two cars hitting head-on at 55.

The effects of the impact are just as much dependent on what happens immediately after the impact as before, (eg., how the car(s) move after impact), which is the general idea I was trying to give my my original response and the change in kinetic energy comparisons for different before and afters.
« Last Edit: January 24, 2014, 10:41:46 AM by Emilyngh »

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Re: Subcompacts fare poorly in new crash test
« Reply #42 on: January 24, 2014, 10:40:30 AM »
Side note: I have actually done my own personal experiments with driving a car into a concrete wall at 70mph.  Not recommended.
Did you calculate the elasticity of the wall from the bounce-back? Because then I would really be impressed.

I didn't.  It was pretty elastic from the trajectory, though.  I went in at about 45 degrees and came back out at around 45 degrees.  It was an old car that was built like a tank -- well before "crumple zones". 

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Re: Subcompacts fare poorly in new crash test
« Reply #43 on: January 24, 2014, 10:43:45 AM »
Experienced both a crash into a concrete wall (new tires could have prevented that), and into another car at 60mph (they got cut off and slammed on breaks and I had nowhere to go) within a week of each other (yep totalled my car and a rental within a week).  Interestingly enough, both were hit offset frontal impact (this was 09)? The mustang didn't deploy airbags, the focus did.  Focus looked worse for wear, and it was technically smaller than the mustang? Walked away from both without a scratch thankfully.  Quite a week when you go from getting into your first accident, total that car, and then total the rental. Either way,  I don't recommend it.

Of course if you have ever googled "cop deer explodes" I wouldn't mind a reinforced front end on my personal car if I didn't have to sacrifice gas mileage.

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Re: Subcompacts fare poorly in new crash test
« Reply #44 on: January 24, 2014, 01:39:50 PM »
Experienced both a crash into a concrete wall (new tires could have prevented that), and into another car at 60mph (they got cut off and slammed on breaks and I had nowhere to go) within a week of each other (yep totalled my car and a rental within a week).  Interestingly enough, both were hit offset frontal impact (this was 09)? The mustang didn't deploy airbags, the focus did.  Focus looked worse for wear, and it was technically smaller than the mustang? Walked away from both without a scratch thankfully.  Quite a week when you go from getting into your first accident, total that car, and then total the rental. Either way,  I don't recommend it.

Of course if you have ever googled "cop deer explodes" I wouldn't mind a reinforced front end on my personal car if I didn't have to sacrifice gas mileage.

Yes, and in my defense, suddenly switching from a 4 wheel car to a 3 wheel car is something they don't teach you in driver's ed.  I, too, was without a scratch.

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Re: Subcompacts fare poorly in new crash test
« Reply #45 on: January 24, 2014, 04:12:42 PM »
Like I said before, IMO the easiest way to think of it is in terms of kinetic energy.    While two moving cars have twice the kinetic energy of one moving car, that kinetic energy is transformed into the wreck of two cars, instead of one.
I was looking at this wrong.  Didn't make sense until I thought of it as capacitors :)

chasesfish

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Re: Subcompacts fare poorly in new crash test
« Reply #46 on: January 25, 2014, 09:02:34 AM »
Its one thing to consider.

This (among a few other luxuries and the joy of lots of travel) is causing me to work 5-6 more years than MMM and his wife to have at least twice the stash.  This and the comp level relative to stress in my job makes it hard to walk away.


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Re: Subcompacts fare poorly in new crash test
« Reply #47 on: January 25, 2014, 09:44:01 AM »
I drive a sub compact Honda Fit. I drive in the right lane, at the speed limit. I'm always aware of cars and traffic. I've made up my mind that in the event of an impending collision, I'm going to yank the wheel hard right and take my chances in the corn field or whatever is on the right. It's good to have a plan. I fully realize stuff can happen so quickly, I wouldn't have time to yank the wheel. I try not to get myself in that position, by leaving a good gap to the car in front of me.
Pretty sure I'm in the minority on this site of people who have driven a semi tractor trailer. This is one thing they suggest you do in case of an emergency. I actually took the ditch one time because a pickup pulled out right in front of me (how you don't see a peterbilt traveling at 70 mph on a flat road). It was one hell of a rough ride! Ripped the front axle off and when I was finally stopped it was under the trailer tires. I also folded the steering wheel with my hands lol. Totaled the semi but I'm pretty sure that decision saved the pick up drivers life. Thinks happen quick in an accident situation but if you are alert you can  possibly change the outcome.

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Re: Subcompacts fare poorly in new crash test
« Reply #48 on: January 25, 2014, 02:48:10 PM »
And of course the cheapest way to halve your risk of dying in a car accident is to drive half as much.  A safer car is no doubt better, but the real marginal difference in crash survival between an adequately safe modern car and a very safe one is fairly small compared to say, choosing to live in an area where less driving at high speed is necessary in the first place.

 

Wow, a phone plan for fifteen bucks!