Discussion
How do you know how safe a car really is? I've a Daewoo Matiz (impressive, yes), and NCAP rates it as a 3-star car. Yet it only takes a slight gust of wind to knock it off its centre of gravity - it certainly doesn't feel safe. And I'm certain that if I went head-to-head against a heavier 3-star car (say a Peugeot 306), I would come off far worse.
I'm thinking, therefore, that weight plays a large part in this. Unfortunately NCAP don't ram different cars into each other, to compare their merits.
Looking at the classifieds, I could get, say, the first version of the Audi A4 for similar money to my Matiz. NCAP rates it as a 2.5 star car - but surely the added weight would mean it's safer than the Daewoo? Any thoughts?
I'm thinking, therefore, that weight plays a large part in this. Unfortunately NCAP don't ram different cars into each other, to compare their merits.
Looking at the classifieds, I could get, say, the first version of the Audi A4 for similar money to my Matiz. NCAP rates it as a 2.5 star car - but surely the added weight would mean it's safer than the Daewoo? Any thoughts?
i would honestly say u have a fair point there. take some 4x4s for example. some are only a 3 star rating but you would certainly come off worse in a daewoo despite being the same rating. i think the rating is only there fr shell strurcture damage and how the body reacts in the event of a crash eg a pillar doesnt bend as much as the next cars meaning the driver wont be harmed. and things like doors still being able to be opened. certainly in a head on you would have alot more damage if a weightier car was thrown at you. imagine a rear shunt.... not good!!
lots of things to consider.
Heavier cars are more likely to become unstable. Cars that understeer are less likely to crash. If you want the safest cars around you can't go too far wrong with a renault people carrier. nice tough heavy chassis with a low center of gravity and a chassis and set up which will never spur you towards taking risks. On a quick note on the heavier chassis thing. It only makes it safer if it is well designed otherwise a heavier chassis is only more weight perssing on the A pillar in a crash (see 5th gears volvo crash vid)
Heavier cars are more likely to become unstable. Cars that understeer are less likely to crash. If you want the safest cars around you can't go too far wrong with a renault people carrier. nice tough heavy chassis with a low center of gravity and a chassis and set up which will never spur you towards taking risks. On a quick note on the heavier chassis thing. It only makes it safer if it is well designed otherwise a heavier chassis is only more weight perssing on the A pillar in a crash (see 5th gears volvo crash vid)
It's not how bad the car looks after an accident that counts - it's what g forces the occupants have been subjected to. For those to be a minimum you need a nice collapsible car which might even tolerate some collapse into the passenger compartment. If the car looks a wreck afterwards that's probably a good thing.
paddy27 said:
You can't compare crash ratings from one class to another with NCAP. A 3 star rating for a small city car is not the same as a 3 star rating for a Range Rover.
What he said.It actually states somewhere on the NCAP website about weights, and how a heavier car is generally safer.
Buy an early BMW E39 (1996-2004 5 series). Cheap to buy, but with a 4 star NCAP rating, airbags everywhere and a weight of around 1500kg, they are very safe cars.
bazking69 said:
It is nothing to do with the weight or size of the car. It is all to do with the cell and safety structures in place on the vehicle.
generally spaceframe chassis are the safest especially at high speed (much over 80 mph and some monocoque chassis tear apart like paper spaceframes are much better at preserving a survival space and absorbing higher impacts. At lower speeds impacts will be rougher and more expensive though because there is less in the way of engineered flexibilityEdited by ctallchris on Wednesday 7th April 16:10
saaby93 said:
It's not how bad the car looks after an accident that counts - it's what g forces the occupants have been subjected to. For those to be a minimum you need a nice collapsible car which might even tolerate some collapse into the passenger compartment. If the car looks a wreck afterwards that's probably a good thing.
being as polite as i can, this really isnt very true. The most important thing is how well the passanger compartment retains its shape (see the vid of renault modus vs volvo estate). the g-force felt in a crash will be very similar in most vehicles, the important thing is whether the pedals / steering wheels etc remain where the should, or get pushed into the occupents.I always thought part of the reason that modern cars are so much bigger is so that deceleration can be achieved less severely to the occupant/s (reducing internal organ damage) by making crumple zones that absorb the impact but with minimal intrusion into the passenger compartment.
My folks had a Matiz which was unbalanced by heavy winds whilst exiting a roundabout which caused my dad to loose control of the vehicle and spin. It wasn't a huge crash as the speed was fairly low. I had driven the car on a few occasions and although it was very economical and surprisingly roomy it was not what I would describe as planted even without heavy winds.
My folks had a Matiz which was unbalanced by heavy winds whilst exiting a roundabout which caused my dad to loose control of the vehicle and spin. It wasn't a huge crash as the speed was fairly low. I had driven the car on a few occasions and although it was very economical and surprisingly roomy it was not what I would describe as planted even without heavy winds.
jimmy306 said:
saaby93 said:
It's not how bad the car looks after an accident that counts - it's what g forces the occupants have been subjected to. For those to be a minimum you need a nice collapsible car which might even tolerate some collapse into the passenger compartment. If the car looks a wreck afterwards that's probably a good thing.
being as polite as i can, this really isnt very true. The most important thing is how well the passanger compartment retains its shape (see the vid of renault modus vs volvo estate). the g-force felt in a crash will be very similar in most vehicles, the important thing is whether the pedals / steering wheels etc remain where the should, or get pushed into the occupents.A bit of intrusion may reduce the g enough to leaev you alive with broken feet.
With no intrusion you can look perfect but internal organs disconnected
saaby93 said:
jimmy306 said:
saaby93 said:
It's not how bad the car looks after an accident that counts - it's what g forces the occupants have been subjected to. For those to be a minimum you need a nice collapsible car which might even tolerate some collapse into the passenger compartment. If the car looks a wreck afterwards that's probably a good thing.
being as polite as i can, this really isnt very true. The most important thing is how well the passanger compartment retains its shape (see the vid of renault modus vs volvo estate). the g-force felt in a crash will be very similar in most vehicles, the important thing is whether the pedals / steering wheels etc remain where the should, or get pushed into the occupents.A bit of intrusion may reduce the g enough to leaev you alive with broken feet.
With no intrusion you can look perfect but internal organs disconnected
The idea of a modern car is that you have two structures. One to absorb the gforces and one to stop the people getting crushed you don't mix and match the two. In the smart car crash the crumple zone did its job and so did the safety cell. To reduce the grofces on the occupants you work to increase the effectiveness of the crumple zone rather than purpousely weakening the safety cell
If you crash a 2.5 tonne Landrover into an 800kg Matiz head-on, even if they both have the same NCAP rating, the Landrover will have more momentum and is likely to slow less suddenly than the Matiz which will go suddenly into reverse when smashed from the front by something heavier, subjecting the occupants to more severe forces.
That said, if you crash into a tree, you should in theory be exposed to the same risks in either vehicle.
At this point I will say that unfortunately this fact leads to the "Volvo driver mentality" whereby an arms race develops to have the heaviest and therefore "safest" cars, which I think is far from ideal.
That said, if you crash into a tree, you should in theory be exposed to the same risks in either vehicle.
At this point I will say that unfortunately this fact leads to the "Volvo driver mentality" whereby an arms race develops to have the heaviest and therefore "safest" cars, which I think is far from ideal.
Mr Gear said:
At this point I will say that unfortunately this fact leads to the "Volvo driver mentality" whereby an arms race develops to have the heaviest and therefore "safest" cars, which I think is far from ideal.
Rather than heaviest was it Volvo that introduced bumpers mounted on shock absorbers and crumple zones to genetly decelerate the occupantsAnother swedish marque has bumpers mounted on sliding bolts with foam energy absorbing decelaration blocks
saaby93 said:
Mr Gear said:
At this point I will say that unfortunately this fact leads to the "Volvo driver mentality" whereby an arms race develops to have the heaviest and therefore "safest" cars, which I think is far from ideal.
Rather than heaviest was it Volvo that introduced bumpers mounted on shock absorbers and crumple zones to genetly decelerate the occupantsAnother swedish marque has bumpers mounted on sliding bolts with foam energy absorbing decelaration blocks
BriC175 said:
paddy27 said:
You can't compare crash ratings from one class to another with NCAP. A 3 star rating for a small city car is not the same as a 3 star rating for a Range Rover.
What he said.It actually states somewhere on the NCAP website about weights, and how a heavier car is generally safer.
Buy an early BMW E39 (1996-2004 5 series). Cheap to buy, but with a 4 star NCAP rating, airbags everywhere and a weight of around 1500kg, they are very safe cars.
- the NCAP test more or less represents a head on collision with a vehicle of equal weight. A small car with a 5 star rating will not necessarily be safer in a head on with a heavy, 3 star luxobarge/4x4/MPV. It also incorporates safety systems into its score, so you might want to look at the direct crash test scores rather than the overall ratings.
- Ideally, you want a car that collapses and absorbs energy up until the point at which it will start intruding into the passenger survival space. A car that is too stiff will cause internal injuries from deceleration, and one that is too soft will simply squash the occupants. Open or closed casket basically.
- Remember that it is not just the crumple zone of your own vehicle that absorbs energy in a head on crash, it's the deformed length of both vehicles. A stiffer vehicle will 'win' against a softer vehicle and make/extend a crumple zone out of it.
- In a head on with a non deformable object (e.g. a tree), NCAP results are likely more relevant, but survivability still based on the vehicle's stiffness against its weight, and with the element of doubt given a choice of high scoring NCAP cars I'd rather be in the biggest one with the most amount of car in front of me.
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