D
Dianelos Georgoudis
Guest
Recently (October 14, 2003) the National Highway Traffic Safety
Administration (NHTSA) released a study about vehicle safety and
weight. See:
http://www.nhtsa.dot.gov/cars/rules/regrev/evaluate/pdf/809662.pdf
As expected, the NHTSA study did find that heavier vehicles are safer
for their occupants when they crash with a lighter vehicle. This is
well known, and many people buy SUVs thinking that their weight gives
them a safety advantage. Some publications stress this fact (for
example one by USA Today is titled "Lighter cars mean more deaths" so
many people who drive SUVs may feel reassured).
In fact, as far as SUVs go, the NHTSA study could not have been more
unfavorable. Using real world statistics about tens of millions of
vehicles over several years they prove that the overall safety of SUVs
is worse than of lighter passenger cars. One of the reasons is that
SUVs have a much higher tendency to roll over. This means that many
people spend more to buy a SUV, spend more on gas, and also endanger
others, without much any advantage for themselves. The relevant
numbers are:
Vehicle type Average weight Driver fatalities
(pounds) per billion miles
Mid-size 4-door car 3,061 5.26
Large 4-door cars 3,596 3.30
Small 4-door SUVs 3,147 5.68
Mid-size 4-door SUVs 4,022 6.73
Large 4-door SUVs 5,141 3.79
So it is more probable that you will be killed in a small or mid-size
SUV than in a mid-size car that weights less. Only large SUVs are
safer for their drivers than mid-size cars, but they are less safe
than large cars, even though large SUVs are 1,500 pounds heavier!
These are amazing numbers. The prorated figures, which take into
account the fatalities in other vehicles involved, are, as expected,
even worse.
The study does show that SUVs are safer than small and very small
cars, which have a disadvantage only because there are so many much
heavier vehicles around. Very few people who end up buying a SUV were
thinking of maybe buying a small or very small car, so this advantage
is irrelevant. Pound for pound SUVs are always less safe for their
passengers.
Even when comparing SUVs only, more weight is not always better.
Significantly, small SUVs are safer for their drivers than mid-size
SUVs, even though the latter weight 900 pounds more. I suppose small
SUVs are more car-like and therefore avoid some of the safety
disadvantages of the SUV design.
If you care about your personal safety then, clearly, the best
strategy is not to use a SUV but to use a mid-size or large passenger
car.
Of course, the safest strategy for society would be to put an upper
limit to the weight of passenger cars: then we all would drive safer,
spend less money on cars, spend less on gas, protect others, protect
the environment, and be less dependent on unstable oil-producing
countries. Limiting the weight of vehicles is a
win-win-win-win-win-win proposition. Vehicles that have to be heavy
(such as trucks, heavy duty off-roaders, buses, etc) should have their
top speed electronically limited to low levels as to not endanger
other vehicles on the asphalt.
Administration (NHTSA) released a study about vehicle safety and
weight. See:
http://www.nhtsa.dot.gov/cars/rules/regrev/evaluate/pdf/809662.pdf
As expected, the NHTSA study did find that heavier vehicles are safer
for their occupants when they crash with a lighter vehicle. This is
well known, and many people buy SUVs thinking that their weight gives
them a safety advantage. Some publications stress this fact (for
example one by USA Today is titled "Lighter cars mean more deaths" so
many people who drive SUVs may feel reassured).
In fact, as far as SUVs go, the NHTSA study could not have been more
unfavorable. Using real world statistics about tens of millions of
vehicles over several years they prove that the overall safety of SUVs
is worse than of lighter passenger cars. One of the reasons is that
SUVs have a much higher tendency to roll over. This means that many
people spend more to buy a SUV, spend more on gas, and also endanger
others, without much any advantage for themselves. The relevant
numbers are:
Vehicle type Average weight Driver fatalities
(pounds) per billion miles
Mid-size 4-door car 3,061 5.26
Large 4-door cars 3,596 3.30
Small 4-door SUVs 3,147 5.68
Mid-size 4-door SUVs 4,022 6.73
Large 4-door SUVs 5,141 3.79
So it is more probable that you will be killed in a small or mid-size
SUV than in a mid-size car that weights less. Only large SUVs are
safer for their drivers than mid-size cars, but they are less safe
than large cars, even though large SUVs are 1,500 pounds heavier!
These are amazing numbers. The prorated figures, which take into
account the fatalities in other vehicles involved, are, as expected,
even worse.
The study does show that SUVs are safer than small and very small
cars, which have a disadvantage only because there are so many much
heavier vehicles around. Very few people who end up buying a SUV were
thinking of maybe buying a small or very small car, so this advantage
is irrelevant. Pound for pound SUVs are always less safe for their
passengers.
Even when comparing SUVs only, more weight is not always better.
Significantly, small SUVs are safer for their drivers than mid-size
SUVs, even though the latter weight 900 pounds more. I suppose small
SUVs are more car-like and therefore avoid some of the safety
disadvantages of the SUV design.
If you care about your personal safety then, clearly, the best
strategy is not to use a SUV but to use a mid-size or large passenger
car.
Of course, the safest strategy for society would be to put an upper
limit to the weight of passenger cars: then we all would drive safer,
spend less money on cars, spend less on gas, protect others, protect
the environment, and be less dependent on unstable oil-producing
countries. Limiting the weight of vehicles is a
win-win-win-win-win-win proposition. Vehicles that have to be heavy
(such as trucks, heavy duty off-roaders, buses, etc) should have their
top speed electronically limited to low levels as to not endanger
other vehicles on the asphalt.