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Obviously people are buying suvs more than ever but are they correct in their thinking that they are safer on public roads vs buying a sedan?
It depends on the kind of crash. For a car-to-car crash, the larger and heavier car is generally safer because the car larger car experiences lower peak decelleration. In car-to-barrier crashes, the lighter car generally is safer because the ratio of crush zone to vehicle mass is better. A typical 4000 pound car does not have 33% greater crush zone depth than a 3000 lb car, yet it has to absorb 33% more energy in the crash. Also, all other things being equal, lighter cars corner and brake better than heavy cars, so they are more likely to avoid a crash, which is the safest outcome. you can also judge car crash safety by looking up their government crash ratings at the NHTSA site. You will see that crash safety scores are not always proportional to vehicle size.
Mr Roth, hope you are doing well amist the current events. Was worried that you didn’t reply back in a while.
How come the crush zone for suvs isn’t larger if its a larger car?
Is it safe to say that in general that suvs are safer than midsized sedans? Or no.
Is the NHTSA a credible source of information vs the IIHS? Because the IIHS gives ratings to the headlights based on things that arn’t possible because of how the headlights work.
The crush zone of SUV’s and other large cars are larger, but in general, the increase is not a large as the increase in mass. The energy to be absorbed in a crash is directly proportional to the mass of the car. A small car has all of the room in front to accommodate the engine and transmission, accessory drive, radiator and fans. The much heavier SUV does not (usually) have an increased crush distance between the driver and the front bumper that is proportional to the increased mass. Some may, and you can judge the overall crash effectiveness by looking at the NHTSA frontal crash scores. The IIHS can be a useful source of crash effectiveness, but I don’t trust them as much, because they are working for the insurance industry and do not always follow rigorous testing methodology.
As far as SUV’s safety compared to midsized sedans, I have to go back to my original assessment: it depends on the type of crash, and sedans with their better handling and braking are significantly better at avoiding crashes. Just look at the published stopping distance difference between a Chevy Suburban and a Toyota Camry.
Ahh I see now. Where does most of the added mass on the SUVs come from?
What do you personally drive?
I can’t find the publication on the stopping distance.
You can find all of the performance parameters (test results) for almost any car by going to the road test section of the car magazine web sites. The USA ones are: Car and Driver, Road and Track, Motor Trend, and Automobile.
I personally drive sedans and sports cars: Hyundai Ioniq, Mazda 3, and Toyota MR2 Spyder. If I need a van or pickup truck, I rent it. I have driven many SUV’s and I do not like driving them.
Most of the added mass in SUV’s is in the entire Unibody structure. The larger a structure is, the more difficult it is to make is stiff and strong. This is just the science of structures. Structures do not just scale up. As you try to scale up a structure it gets flimsier, so you have to make the structural sections larger and heavier.
Dave
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