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IIHS Picks Safest Vehicles

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Comments

  • patpat Posts: 10,421
    The preceding 15 or 16 posts have been moved from another discussion. :)
  • backybacky Twin CitiesPosts: 18,624
    OK, so here's an analogy: suppose there are two car-sized boxes. One weighs 10 pounds. The other weighs 4000 pounds. Both run head-on (maybe at an offset) into another box that weighs 3000 pounds, with each box traveling at 20 mph. Which box do you think would have the most damage? The box that weighs 10 pounds, or the box that weighs 4000 pounds? Or would they suffer the same amount of damage?

    If you had a choice of being hit by the 10 pound box or the 4000 pound box, which would you choose?

    These are extreme examples of course, but do you see that the weight of the car does factor into the test if the car is moving?
  • jeffyscottjeffyscott Posts: 3,855
    Yes, of course the weight of the cars is a factor in a collision. This is a weakness of the current frontal tests. They adequately simulate a single vehicle crash or a crash with a similar weight vehicle.

    If a "good" rated civic has a head-on crash with lower rated, but 1000 pound haevier car (eg Impala)...which will prove to be safer. I'm pretty sure it would be the Impala. Now what if the weight difference is only 500 pounds? Is an "acceptable" Fusion safer (based on frontal crash test results) than a "good" civic? I'd guess probably...but it is only a guess.

    In a two vehicle accident the weight of both vehicles is a factor, because weight (actually mass :) ) is a factor in energy and momentum. So if a test has moving standard simulated vehicle crashing into a moving test vehicle, yes the weight of the test vehicle would be a factor...but this is just as it is in the real world.

    IIHS managed to come up with a moving sled for side impacts, not sure why something similar would not be done frontal. Design something mimicing the front end of 3000 or 3500 pound car (and/or truck/suv) and crash it into the front end of a moving test vehicle.
  • backybacky Twin CitiesPosts: 18,624
    ...yes the weight of the test vehicle would be a factor...but this is just as it is in the real world.

    OK, then we are in agreement I think. If the IIHS were to implement a frontal test as you have suggested, where a moving car hits a moving barrier, then the tests could not be compared across weight classes. That was the original question we were discussing. The question was not whether the IIHS could design such a test and if it would be useful, but just whether the results could be compared across weight classes.
  • jeffyscottjeffyscott Posts: 3,855
    I don't see why you say it could not be compared across weight classes. :confuse:

    If they smashed a 3000 pound device into a Civic, the results would simulate what would happen in the real world if the civic were hit by a 3000 pound vehicle.

    If they smashed the same 3000 pound device into an Impala, the results would be indicative of what would happen in the real world if the impala were hit by a 3000 pound vehicle.

    Comparing them would tell you how one would do relative to other in a real world frontal collision with the same 3000 pound vehicle.
  • backybacky Twin CitiesPosts: 18,624
    Didn't you just agree that weight would be a factor if both the cars and the sled were moving?? :confuse: :confuse: :confuse:

    We weren't talking about smashing a device into a car. I thought you had proposed taking a moving device and smashing it into a moving car.

    I'm done on this topic.
  • jeffyscottjeffyscott Posts: 3,855
    I thought you had proposed taking a moving device and smashing it into a moving car.

    Yes, and this would mimic what would happen when a 3000 pound moving car smashes into the other moving (tested) car in the real world. Civics do not collide only with other Civics and Impalas with other Impalas in the real world.

    What is wrong with the idea of a standardized test that mimics a 2 vehicle accident? The Civic owner is just as likely to collide with a 3000 pound vehicle as is the Impala owner.
  • jim314jim314 Posts: 491
    To a first approximation it is the closing velocity of the two given vehicles that is relevant in determining the effect of a collison, and not their motion relative to the ground.

    Consider a head-on collision between a specific 4000-lb car and a specific 2000-lb car. The following different scenarios result in the same damage to the each of the cars, and in each case the crash accelerations will be twice as much to the smaller car.

    1. 4000-lb car is stationary and is hit head-on by the 2000-lb car travelling at 40 mph

    2. 2000-lb car is stationary and is hit head-on by the 2000-lb car travelling 40 mph

    3. 4000-lb car travelling 20 mph and 2000-lb car travelling 20 mph collide head on.

    The way to think of a vehicle collision, to a good first approximation, is to think of them as being out in space where there is no local frame of reference for speed.
  • jim314jim314 Posts: 491
    Correction to #111

    2. 2000-lb car is stationary and is hit head-on by the 4000-lb car travelling 40 mph.

    Addition: Remember that a 4000-lb car will in general be larger (and hence have a larger crush zone) and will in general be stronger (stiffer) than the 2000-lb car. This will reduce the likelihood of intrustions into the passenger space of the larger car.

    The two vehicle will exert equal but opposite collision forces on each other, but since F = ma the resulting accelerations (or changes in velocity) caused by the crash will be different and will be inversely proportional to the masses. This means that unrestrained occupants of the 2000-lb car will experience twice the force if they contact the inside of their own car than unrestrained occupants of the larger car. Unless an occupant is wholly or partially ejected from their car what injures them is the collision of their body with the inside of their own car.
  • rockyleerockylee Posts: 14,011
    Ford, GM fall off list as insurance industry group toughens criteria to promote improvements.

    http://www.detroitnews.com/apps/pbcs.dll/article?AID=/20061121/AUTO01/611210365/- 1148/AUTO01

    Rocky

    P.S. It's all a buncha B.S. because some cars don't have ESC. :mad:
  • rockyleerockylee Posts: 14,011
    ARLINGTON, Va. — Thirteen cars and trucks from foreign manufacturers — including the Kia Sedona and Hyundai Entourage — won Top Safety Pick honors for 2007 models from the Insurance Institute for Highway Safety.

    http://www.edmunds.com/insideline/do/News/articleId=117652

    Rocky
  • jeffyscottjeffyscott Posts: 3,855
    One thing I don't get...they just came up with the gold and silver concept last year and now they already have changed to something different? :confuse:
  • backybacky Twin CitiesPosts: 18,624
    Not entirely different, but they have upped the ante as automakers have continued to improve the safety features of their cars. It was not long ago that active head restraints and ESC were pretty rare in non-luxury cars. Now they are becoming more common, with moderately-priced cars such as the Civic, Sentra, and Elantra having standard active head restraints and vehicles like the Tucson and Sonata having ESC standard. So now the IIHS is telling automakers, "Get with it! You did well on the frontal and side crash tests, Silver and Gold award winners, but times have changed and it will take more now to win our 'top pick' award."
  • jeffyscottjeffyscott Posts: 3,855
    Right, but I mean they are not using the gold and silver terminology. Now it is just something "best pick" and "also rans"
  • rockyleerockylee Posts: 14,011
    http://www.detnews.com/apps/pbcs.dll/article?AID=/20070501/AUTO01/705010330/1148-

    Oh boy....oh boy....Ford, sure is taking "bold moves" in it's advertising. :surprise:

    Rocky
  • orbit9090orbit9090 Posts: 110
    >> It's amazing not to see VW group receive the highest (safety) honors.

    Not surprising to me.

    After all, it's really not safe to be driving around in a Volkswagen :lemon: having no brake-lights
    or turn-signals after the "affordable German engineering" electrical system shorts out.

    .
  • orbit9090orbit9090 Posts: 110
    Ouch!

    image

    Thanks in part to the IIHS, vehicle structural crash safety has greatly improved in recent years,
    in contrast to the dismal results from a 40mph crash test of a Ford Tempo.
  • fintailfintail Posts: 32,909
    Wow, that thing looks to have lost a couple feet of wheelbase. Scary.

    Reminds me of the tests of the late 90s F-150 extra cab that folded up like a pop can.
This discussion has been closed.