Technical Banging out dent in spare wheel well

[UFI]

Had this been a previously crashed car, however well executed the repair work, I doubt very much she would still be alive.

Even if the repair was to the boot floor?

 

[Most Easterly Pandas]

Even if the repair was to the boot floor?

Quite possibly in some extreme cases, energy dissipates over the 'whole' vehicle, not just the area that's impacted.

Watch some ncap crash tests and you'll see how the rear panels often permanently bend and flex while absorbing the impact from a front end collision.

 

[306maxi]

Even if the repair was to the boot floor?

You've got to remember that it's a whole structure. It's a little like an egg, quite strong and able to withstand quite a bit of force end to end, but a little crack in the side and its ability to withstand force is severely reduced.

 

[UFI]

JR's wife had a lucky escape in a supermini, what if she/the other had driver been travelling a few km/h faster?

In an S-Class that likely would have been a walk away accident.

So where does that leave us?

It's fair enough to point out that the repair in question is far from ideal, but it could well still be the safest car the OP can afford. We can't all drive the best and superminis, 5 star or not, don't fair especially well in real world accidents.

 

[UFI]

I have often considered we would all be better off on the roads if all the vehicles had big sharp spikes that flew out instead of airbags and crumple zones.

People might drive a bit more carefully?

I don't think you'd need to go quite that far. You could simply ban full cover insurance. You'd drive more carefully if you knew you'd be 100% responsible for any damage to your own car. It would also get those people who have an annual accident off the road.

I have a few cars so if I lost my NCB I'd be out of pocket around $10,000... I drive carefully, I'll probably add NCB protection at the next round of renewals now that I think about it.

 

[Most Easterly Pandas]

JR's wife had a lucky escape in a supermini, what if she/the other had driver been travelling a few km/h faster?

In an S-Class that likely would have been a walk away accident.

From what JR has said it was, and what it looks like, it was a walk away accident physical injury wise.

Bringing vehicle size into the equation has nothing to do with a botched previous repair TBH. Likewise hit something like a tree etc and again its irrelevant. The only time size matters is when hitting another vehicle, as the one will the bigger mass normally comes off better.

 

[jrkitching]

From what JR has said it was, and what it looks like, it was a walk away accident physical injury wise.

Nothing walk away about it - fractured sternum, internal injuries, a night in the ICU, three weeks bedbound and two months off work. Despite the passenger compartment maintaining integrity, the accident was only just survivable.

In a previously crashed & repaired car, she wouldn't have had a chance.

UFI's point is that not everyone can afford the safest possible option, which I guess is why he brought the S-class into this. With a longer bonnet, you have more space to play with and can design the crumple zone to reduce the deceleration force on the occupants.

I'm a believer in free choice, and Darwinian evolution - if folks want to patch up a salvaged car & risk their own neck in it, I have no issue with that. My concerns are for their passengers, and anyone who subsequently buys the car if they sell it on.

 

[Most Easterly Pandas]

Nothing walk away about it - fractured sternum, internal injuries, a night in the ICU, three weeks bedbound and two months off work. Despite the passenger compartment maintaining integrity, the accident was only just survivable.

In a previously crashed & repaired car, she wouldn't have had a chance.

Blimey, my mistake!

Out of interest what did it hit, and what sort of speed?

 

[jrkitching]

Out of interest what did it hit, and what sort of speed?

Another supermini, IIRC it was a Polo. The Polo was pushed across the carrigeway straight into her after being hit by a 7 series which pulled out of a side road without looking. A couple of local bystanders had to stand in front of the BMW to stop it driving away. The drivers of the other two cars left the scene by ambulance.

Police reckon both cars were doing about 25mph at the time of impact.

 

[Sweetsixteen]

We can't all drive the best and superminis, 5 star or not, don't fair especially well in real world accidents.

Just as a tack never did get the better of a hammer.

Reminds me of the RollsRoyce owner who only ever drove a couple of miles a day. He was asked why he didn't buy a small car. He replied, 'This thing weighs over two tons. A mini weighs just over half a ton. If I hit a mini, who will suffer most?'

Laws of physics come into play with every accident!

 

[UFI]

Bringing vehicle size into the equation has nothing to do with a botched previous repair TBH. Likewise hit something like a tree etc and again its irrelevant. The only time size matters is when hitting another vehicle, as the one will the bigger mass normally comes off better.

No. Although mass is a factor when dealing with two vehicle collisions, in a collision with a tree or concrete block, the S-Class is going to be about 3x better off than a supermini.

The 500 only has maybe a foot of usable crumple space before it hits the survival cell. The big luxury car has maybe three feet of crumple space. It decelerates much more slowly in an impact than the supermini. If the survival threshold is around 200G in a 500, the S would only peak at around 1/3rd of that in the same collision, with the same immovable object.

In a collision between a supermini and a luxury sedan the physics are much more dire.

But the point I was making is that an S, A8, Volvo etc has much better design and technology, they're crash tested in every possible way for real world accidents. A supermini is designed to score 5 stars and that's it. A 500 only scores 5 Stars for it's class, if it were put in the luxury car class it would likely score 1 Star As an example of how technology helps in the high end cars, Mercedes are working on inflatable metal panels that deploy on the exterior of the vehicle to extend the crush space.

It's a bit like official MPG figures, cars are built to cheat the system. IMO NCAP is far more misleading, and with everything now scoring 5 stars, there's no incentive to actually build a safer car.

My point all along has been that it's all relative. JR's accident might well have been much worse in a repaired car, but then the C1 was only a 4 Star car in the lowest performing class. You have to draw your own line in the sand as it were because the idea that 'this is safe' and 'this is unsafe' is really the same as 'how long is a piece of string?' If this were a crashtest safety forum, we'd all be horrified that anyone drives a 500 on a public road at all.

If safety were a real priority, I'd go up at least a size from a 500, the longer the crumple zones, the gentler the crash.

 

[PuntoHowTo]

My other Half crashed her car and fractured her sternum that's was 30mph front end, and the car faired up well (fiat mk2b punto) compared to the Audi A4 she hit, though both were still written off.

Given my other half is an A&E doctor they look at a lot of crashed cars to understand the 'mechanism of injury' if someone if brought in its very useful to them to understand how damaged the car was and how it relates to the patient injuries.

Officially anything about 50G for a fraction of a second is usually fatal, without any other injury, it's the force that causes blood vessels to rupture and bleed and organs to become damaged, essentially anything above 40G is likely to seriously damage your eyes, so transfer that to other organs and you're in a bad bad way.

That say into a brick wall at 70mph you may experience as much as 25+G but compare a smart for two with a merc cls and you're going to see a huge difference in the G because of the disappation of energy round the safety cell. (I'm really not sure where you got your figure of 200G UFI but you'd be very dead way before you reached that point.

So if you are going to compare a big car to a little car, the safety depends on how the accident energy is managed. And while s big car may manage that in just the front crumple zones a smaller car may be designed to disapate the energy arround the cell, into the boot through the roof etc. but for a crumple zone to be effective it must crumple and also resist the crumple. It's no good having a big crumple zone if only a small amount of force destroys the zone. This is why new cars like a 1000kg fiat 500 fair much better than say a 2 ton 1970s Daimler. The new car is designed to crash, the old car safety was of little concern. Many crash tests have shown that when a small new car crashes into a bigger heavier old car, the occupants of the old car usually end up with massive leg and chest unjuries, the new car drivers would walk away unharmed.
This is possible because the new car channels the accident energy away from the cabin.

So imagine a coke can crushed and then restraightened, the previously crushed can is not going to resist being crushed again as well as a brand new coke can. The crushed can has weaknesses and folds in the metal you simply can't remove without replacing the metal. Basically you won't get a crushed coke can perfect again. So with this in mind it's exactly the same with a repaired car. Unless the metal is replaced the cracks, kinks fatigue etc it's there in the metal so if hit a second time the car will crumple easier absorbing less of the energy, and transferring less through the rest of the car, more of the energy will be transferred to the occupants because it won't be absorbed.

In the situation I dispute that a repaired newer car be safer than an older car, you can buy an older Renault or similar with a 5 star rating for the same money as a damaged fiat 500 easily, if that's what you are after.

Anyway in this case I really don't care if the OP Wants to drive arround in a car that's not as safe as new but at some point the car will be sold again and the 'Cat D' will have to be declared, however usually you would say cat D repaired but in this case it will not be repaired to the standard your might expect and as such someone might end up in a car that's not as safe as it should be, 500s are a go to car for women with young families, so the question you need to ask is would you be happy to have children in the back seat of this car when it's simply been hammered out to look straighter?

I would happily say my Undamaged 54 punto would be far safer than a badly repaired 08 fiat 500

Also euroncap doesn't look at the size or shape of the car when they crash test it, all cars are equally tested and rated according to performance, so a 4 start luxury merc is comparable to a 4 star supermini they put them. Into there relevant classes so you can compare cars of an equal size, if you're looking to buy a fiat 500 you don't need bombarding with info on a ford mondeo in a different class youre not interested in.

So crash a bigger car into a smaller car?

Bigger car = greater mass so in an accident mass = energy = car needs to absorbe/disapate more energy to perform to get its 5 star rating.
A small car needs to do less to get its 5 star rating.
In a head on smash 5 star versus 5 star. The big bulky car will be absorbing a big chunk of its own energy as it's been designed to absorb/disapate more than a smaller car.

The issue comes when there is an imbalance, so a 1992 ford Sierra that might weigh 1500kg with maybe a 1 or at most 2 star ncap rating is never going to fair well against a 800kg supermini with a 4-5 star rating. The smaller car will basically punch a hole through the old unsafe car no matter that it weighs more. The occupants of the supermini might experience more G but the occupants of the heavier Sierra could have the car crush in on them.

I guess what I'm trying to say in this ramble, is that a car is designed to be crashed these days and when/if it does it's designed to respond In a certain way. You can never make a piece of sheet steel that been damaged, 100% as original simply by hammering it back into shape.

It will never be as safe as new or imo as safe as an Undamaged but older car.

 

[UFI]

(I'm really not sure where you got your figure of 200G @UFI but you'd be very dead way before you reached that point.

Race car drivers routinely walk away from 100G plus accidents. Part of the discrepancy depends on where you put the G sensor. It's also dependent on the sample rate of the sensor. It's really not 'x' G that kills you but x G against y time. You can survive very high G if the time only a millisecond.

During practice for the 1977 British Grand Prix at Silverstone, for instance, David Purley was briefly exposed to a force estimated at 179.8g after his throttle stuck open at Becketts Corner.

In the subsequent impact, his car decelerated from 108mph to zero in a distance of little more than two feet. He suffered serious leg, hip and pelvic injuries, but recovered to race again

http://www.telegraph.co.uk/motoring/motorsport/7681665/Formula-One-drivers-feel-the-G-force.html

 

[UFI]

Also euroncap doesn't look at the size or shape of the car when they crash test it, all cars are equally tested and rated according to performance, so a 4 start luxury merc is comparable to a 4 star supermini

So the experts on this forum were wrong? I didn't 'know' that until I read it here, apparently I didn't know it because it wasn't true. Where were you then?

True Renault's Megane got 5 Stars a long time ago (but didn't perform as well as the 500), but the ratings were changed were they not, such that each car tested under the old system was shuffled down by one star. The Renault Kangoo got 4 stars when originally tested, but when the Mercedes Citan Launched it only scored three stars under the new system. Mercedes made changes and the car was retested and scored 4 stars again. The EuroNCAP site still shows the Kangoo as a four star car.

The 500 is also rated under the old system so might not actually be a 5 star car anymore? I notice the current Megane only manages three stars despite out performing the 500.

 

[Sweetsixteen]

Underlying message from this informative thread?
Sell Fiat, buy Merc!

 

[Sweetsixteen]

My scant knowledge of G forces suggests that the length of time a person undergoes high G's is a major factor in his survival rate. Whereabouts on the body the highest G force is experienced also plays a part. For example, a boxer receiving a punch gets a localised very high G, possibly up to 200g, but for an extremely small time on a compact area. Survival rates here are high.
A car crash can give an occupant extremely high G forces - measured at up to 200g - for an instant, like the racing driver example above - with high survival rates.
If, however, a human experiences far lower G forces for an extended period - ie, under 50g for several seconds - this could be fatal.
The rate and extent of acceleration seem to me to be the significant factors, not just the highest G force experienced.

 

[TuX]

Fiat bravo is supposed to be a 5* crash rating, all working.

I would never suggest driving it around with the airbag warning light on . That indicates at best the acu might set something off in a crash, maybe, if it felt like playing along.

5*crash ratings of course include all the airbags/safety stuff. +it helps having a modern 206 vs an old 240, no contest.

They don't test for, i don't know why, but last night the Bourne ultimatum, he at least twice spun backwards with head against the headrest/seat to break through roadblocks. That's where I learn facts

 

[PuntoHowTo]

If the survival threshold is around 200G

My remark on this point is that 50G is considered the survival point for the majority of people. People's ability to tolerate G differs massively my friends husband flys the euro fighter for the RAF I'm sure he'd fair much better then me in respect to G-forces.

Kenny Bräck sustained a force of 214G in 2003 in a 200mph crash and suffered multiple fractures all over his body, he survived but he certainly didn't walk away, so yes you can find exceptions to the rule but what you can't say is 200G is a cut off for survivability.

Race car drivers routinely walk away from 100G plus accidents. Part of the discrepancy depends on where you put the G sensor. It's also dependent on the sample rate of the sensor. It's really not 'x' G that kills you but x G against y time. You can survive very high G if the time only a millisecond.

They say anything above 10G over a minute can be fatal or at least do irreparable damage but it's very hard to sustain prolonged G forces, a fighter pilot again might see 14G for a couple of seconds in a tight turn in a high speed crash 70ish mph you're not going to see anything above 100G and certainly not for more than a fraction of a millisecond, crumple zones are designed to prolong the G-force time which reduced the g-force value. f1 cars crashing at very high speeds still have crumple zones but are designed more to shorten the g-force time as much as possible.

You could crash a paramount marauder into an immovable concrete block at 40mph as per ncap and you'd probably risk scratching it, but all the accident g-force would be experienced by the driver chest on the seat belt and could be fatal, without any real damage to the car.
To show fith gear crashed two ncap 3 star cars a smart for two and a corsa A into 20 tons of concrete at 70mph the findings of which showed the car stood up well but the forces transferred to the occupants would have been enough to kill

True Renault's Megane got 5 Stars a long time ago (but didn't perform as well as the 500), but the ratings were changed were they not, such that each car tested under the old system was shuffled down by one star. The Renault Kangoo got 4 stars when originally tested, but when the Mercedes Citan Launched it only scored three stars under the new system. Mercedes made changes and the car was retested and scored 4 stars again. The EuroNCAP site still shows the Kangoo as a four star car.

The 500 is also rated under the old system so might not actually be a 5 star car anymore? I notice the current Megane only manages three stars despite out performing the 500.

I'm confused by this 'shuffled down' thing you keep saying?
A 2002 Megane can be bought for £700 and is a 5 star car, it still retains 5 stars there has been no shuffling down. A 2002 megane is tested under the same system as the 500 so they are comparable. Newer cars like the 2014 meganne is ranked under a new system and like the Mercedes has two recorded scores so I'm assuming a similar thing happen Renault made some changes and asked for a retest. In any case it scores 4 stars under the new test procedure. Which doesn't make it any less safe than a 2002 5 star car. Even though the older car is still a euroncap 5 star car. The fiat 500 is still a 5 star car they haven't change the old scores because of a new testing system.

A 2010 Mini Countryman is a 5star car as is the Fiat 500L tested in 2012 but between the two dates ncap upped the test requirements twice so there is quite a difference in test scores between the countryman and the 500L the 500L scores much better on NCap

Yet in the American ncap equivalent the countryman scored better because of its small overlap result compared to the 500L which performed very badly.

So what am I saying ? Well by ncap standards a 2002 megane would perform the same in an accident as a fiat 500, despite the size differences they are tested by ncap the same the only difference being child protection was added. Which the 500 didn't perform as well on as a 2008 Megane which was really only a facelift

So I would maintain that in this argument a £700 Undamaged 2002 Renault megane would be safer than a 2008 on fiat 500 that had been badly repaired given that they are already equal on paper.

But from an Ncap point of view a Mercedes S class is crashed in exactly the same way as a fiat 500, they don't give the merc any special points based on its size or shape, the results from the dummy have to score as well between the two cars to get the same ratings, what NCap does do is award points for additional safety systems so where an S-class with all its electronic gadgetry compared to a fairly simple fiat 500, with the extra points awarded, you could argue the fiat has to perform better in the actual crash tests to get an equal overall score, it's this sort of comparison that a lot of research papers have been written on showing that so called 'safer' ncap cars don't perform so well in the actual crash tests compared to equally overall performing, more simple cars.

 

[UFI]

http://europe.autonews.com/article/...-citan-performs-poorly-in-euroncap-crash-test

The Mercedes-Benz Citan small delivery van has been given three out of five stars in a EuroNCAP crash test.

The van is a derivative of the Kangoo from Renault, which formed an alliance with Mercedes parent Daimler in 2010 that includes commercial vehicles, small cars and powertrains.
The Citan is built at the French automaker's plant in Maubeuge, France. The engines, which Daimler upgraded, are from Renault.


The Kangoo scored four out of five stars when tested in 2008.


Tougher tests
The Citan is the first and only small minivan to be tested this year by EuroNCAP, which has made it progressively more difficult to earn a top score of five stars since 2009.

In 2005 the Megane scored 5 stars:


http://www.euroncap.com/tests/renault_megane_2002/146.aspx


The current Megane is a 3 star car:

http://www.euroncap.com/results/renault/megane/555.aspx

So the 2005 Megane is a 2 star car at best if retested to the current standard. It's still officially a 5 star car, but it's potentially misleading to call it a 5 star car when that wouldn't be the case if retested (and this will only get worse if the goal post are revised annually). The 500 was tested under the same old rules of course, but scored slightly higher than Megane. Most of the discrepancy comes from the Pedestrian and Safety Assist categories. The S-Class hasn't been tested by Ncap, I'd imagine it's features are so far in advance of Ncap that it would be irrelevant.

The safest car I could find is the Golf, but look at the Chev Aveo:

http://www.euroncap.com/results/chevrolet/aveo/2011/437.aspx

93% in safety assist without lane departure warning, autonomous braking or anything out of the norm. There's still a lot of relativity in the ratings.

 

[Sweetsixteen]

So - drive defensively my friends!
The more of us who do it, the less faith we need to put in good old Ncap ratings, G-forces, collision angles, metal fatigue, driver fitness, et al!