A good car to have a crash in…? Part 4

2 Mar

This is the final part in this mini – series on how to choose a car that can save your life.

If you haven’t read parts 1, 2 and 3 then I suggest you do before reading this so that you can make better sense of the points raised in this particular post.

The latest figures released for America and Western Europe suggest that the cars we drive on the road are approximately ten years old on average. Personally, I am surprised to read this. I would have thought that the ‘average’ would have been younger – closer to seven. However, I simply cannot find data that contradicts this claim and so I shall have to accept it.

A good car to have a crash in is one that will maximise our chances of survival and minimise our chances of becoming “KSI” – Killed or Seriously Injured.

At this point, we can all imagine in our minds a few particular cars that we might choose to be in, solidly manufactured by makers who have a long and proven reputation for collision safety research and who build large and well-upholstered cars. ‘Large’ cars? No – hang on – we are already becoming confused.  Just because it is large does not mean that it better protects us from KSI. Yes, it may be scientifically correct that a large car is likely to better survive a collision with a small car, but large cars do not necessarily save us from being KSI. Ask Princess Diana.

We have to look carefully now at a whole range of factors and ‘values’ to understand how to make the best choice.  If “large cars from reputable manufacturers” are good to have a crash in, three questions immediately pop up:

1) Will manufacturers or insurance companies reveal KSI data for these cars?    Answer: No.

2) Is it easier to quickly alter the direction of travel of a large car compared to a small car?  Answer: No.

3) If both large and small cars are driven at 100 kph into an unmovable concrete block, is KSI data identical?  Answer: Yes.

To find out what is really going on with modern cars and to make an informed choice, we must go back and look again at the three ‘interested parties’ involved in a collision: The Car – The Occupants – The Investigation. I call this: “The Facebook Triangle”;  each player has an opposing self-interest. Let me explain it to you.

The car manufacturer works hard to build a car with a low KSI factor, including safety by design, by build quality and by product testing.  In the real world we live in, the manufacturer will only go so far before the budget dictates that they release the car on to the market.

The crash investigator visits cars that have been involved in KSI collisions and tries hard to establish what  factors caused the KSI result. Although the investigator may see obvious reasons for KSI that were not actually  to do with the car itself, for example – a 100 ton tree falling on the car when it was stationary, the investigator will still have to attribute a KSI cause – “car roof structural integrity failure”.

The driver and passengers of the car unintentionally became involved in a collision. Effectively – if we are accurate – the driver ran out of ways of avoiding the collision and therefore became involved. The driver now hopes that the car will protect them as a last resort.

There are three players involved: the manufacturer, the investigator, the driver. All three have totally different aims. The manufacturer is trying to avoid having KSI data attached to its product, the investigator has to attach a cause of KSI to the product. Lastly, the driver (or their surviving relatives) is hoping that the cause of KSI is not attributed to the driver.

By accepting the above scenario, we can see a greater truth emerging:

A mass-produced, affordable commuter car will attract more KSI “hits” than an expensive luxury car simply on the basis that it is generally driven for more miles, driven by a more diverse range of drivers, driven in more diverse circumstances.

So, manufacturers of large luxury cars do not want to reveal accurate KSI data because it might actually show that, mile for mile in the real world, that precise model of car has similar or more KSI hits than a competitor’s standard ‘budget’ car. Manufacturers of standard ‘budget’ cars don’t want to discuss KSI openly for fear that their product gets unfairly associated with a high KSI. We can see their point because many more unskilled or otherwise dangerous drivers will drive their product instead of an expensive luxury car.

Collision investigators have to attribute a cause of KSI. If they keep writing down “…I don’t know but, jeez, the driver was completely like spaghetti once he’d been passed through all the round dials on the dashboard…” they are only hanging on to their jobs by their fingertips. Accuracy is key.

And then, there is the driver. We drivers come in all shapes and sizes and skill levels. The collision investigator and the manufacturer want to ask us – in all seriousness – “…could you have avoided that collision?…”  We rarely answer “Yes.” When looking at KSI data, it is often difficult to separate out the acts of the driver from the behavior of the car. For example, did a car leave the road because it has poor road-holding or handling characteristics or else did the driver fail to use the car’s controls correctly?

Several popular manufacturers currently have cars on the road which, technically speaking, have fatally flawed handling characteristics.

More truth emerges: Insurance companies sift through the data of KSI. They have close access to that accurate data. Do they reveal the accurate, dissected data? Absolutely not. It is competitively sensitive. However, they do often put pressure on manufacturers to improve their products. They sometimes do this quite bluntly by telling the manufacturer to improve a particular car or else the insurer will effectively “kill it off” by use of high insurance premiums.

Conversely, the ‘People Carrier’ design of car emerged partly because insurance companies noted a new KSI trend: where two vehicles collided and one vehicle had its occupants seated higher than the centre of gravity of the other, (say, a conventional car) much of the collision shock passed underneath them. The obvious flaw in this initial advantage was that it canceled itself out if all vehicles were designed in that same way and it also raised the centre of gravity, increasing the chance of the People Carrier turning over.

To find out which car is good to have a crash in, we have to run all the data backwards. Instead of looking at all the shiny cars we have available to us and then wondering which one to drive, we must imagine each one already crashed and stationary, its occupants still inside. By doing so, stark realities become clear that were previously obscure.

All cars perform worse as more occupants and luggage are added to them. Regardless of size, if the car is carrying maximum occupants and maximum luggage, that luggage and those occupants increase the distance needed to stop or evade, increase the kinetic energy that has to be dissipated in the collision, reduce the interior space available to act as a ‘free zone’ where there are no obstructions.

All humans become KSI if their internal organs are subject to an impact above approximately 27mph. When we watch film of cars being crash tested, we see how the manufacturer tries to solve this problem by making the car’s passenger compartment slow down ‘progressively’. This is done  by transferring the impact forces away from the compartment and ‘soaking up’ as much force as possible in the parts of the car that are outside the passenger compartment – the engine compartment and the luggage compartment in particular. These areas are particularly used to make impact shocks to the passengers become more softened.

Airbags and flexible interior trim add more shock-reduction still, so the more of them one has, the better overall. They convert those sudden shocks and impacts into a series of more gradual ones. That passenger compartment has to keep it’s integrity, leaving the passengers with room to move inside it as the actual impact takes place. So, a sophisticated manufacturer can turn a crash at above 30mph into a series of decelerations, each one lower than 25mph, the g-forces dissipated as much as possible within the time frame of the collision.

Drivers and occupants often survive high-speed crashes because their car actually is involved in a series of collisions within that one event and each individual impact is lower than 25mph. For example, suffering a tyre failure at 100mph (lose 10mph), bounce off the railing (lose 15mph), skid diagonally across three lanes (lose 20mph), bounce off a truck (lose 20mph), bounce backwards into another vehicle (lose 20mph) and then skid to a halt (the final 15mph). Far better than hitting one item at 100mph.

Since the vast majority of crashes are head on, it is wise to design the front of a car so that it sequentially changes shape during an accident, altering the onward course of the car. This is best illustrated by looking at a Formula 1 racing car. Notice how the driver sits in a narrow canoe-like pod with a pointed nose? What would happen if two racing cars were to collide head on? The two passenger compartments would slide past each other, decelerating more slowly over a longer time period as  ‘sacrificial’ parts – front wheels and suspension – take the brunt of the forces. Clever stuff.

So some newer cars have their mechanical components angled such that they will fold inwards and downwards, reducing the chance of the vehicle stopping dead or becoming interlocked with another vehicle. Their suspension and wheels will progressively shear off as forces rise, their passenger doors will interlock with their door frames to provide a continuous structure instead of acting as a separate panel.

Walking among the lines of crashed cars in a recovery yard, I became aware that one category of car rarely appeared: the car with four new tyres. It was disproportionately absent. I checked this with my calculator and this car was under-represented by a factor of 75% in a yard made up of 175 cars. Those “missing” cars were not there in the yard because they had managed to stop in time or else swerved to avoid the crash.

Think on that. They never actually got involved in the crash. The crash never happened.

“A good car to have a crash in…?” has been a series of articles intended to help you make informed decisions and good risk assessment. In real life, a good car to have a crash in is a two to three year old medium-sized or large car from a reputable manufacturer, carrying a five-star (maximum) safety rating. Its occupants are average build, seated and belted correctly and relaxing as the airbags explode to meet them.

A good car to avoid having a crash in?  Well, that is a different question!

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