Photo: AFresh1Ever since the SUV craze began in the late 1980s, we’ve all known that heavier vehicles are safer for those driving them, but more dangerous for others on the road. Which is why we all started driving them. Now, in a new working paper, a pair of Berkeley economists have quantified not only the fatality risks of heavier cars for other drivers, but also the costs associated with them. Here’s the abstract:
Heavier vehicles are safer for their own occupants but more hazardous for the occupants of other vehicles. In this paper we estimate the increased probability of fatalities from being hit by a heavier vehicle in a collision. We show that, controlling for own-vehicle weight, being hit by a vehicle that is 1,000 pounds heavier results in a 47% increase in the baseline fatality probability. Estimation results further suggest that the fatality risk is even higher if the striking vehicle is a light truck (SUV, pickup truck, or minivan). We calculate that the value of the external risk generated by the gain in fleet weight since 1989 is approximately 27 cents per gallon of gasoline. We further calculate that the total fatality externality is roughly equivalent to a gas tax of $1.08 per gallon. We consider two policy options for internalizing this external cost: a gas tax and an optimal weight varying mileage tax. Comparing these options, we find that the cost is similar for most vehicles.
Some highlights:
From 1975 to 1980, average vehicle weight in the U.S. dropped almost 1,000 pounds, from 4,060 lbs to 3,228 lbs. By 2005 those reductions had all been gained back, and the average car was as heavy as it was in 1975.
Previous research has suggested that a heavier car fleet is a safer one. This study concludes that tightening fuel economy standards (and thereby reducing the weight of cars on the road) will not increase fatalities, so long as the standards are “footprint based” or unified across cars and trucks. Here’s how:
We quantify the external costs of vehicle weight using a large micro data set on police-reported crashes for a set of 8 heterogeneous states. Unlike the data sets employed in the previous transportation literature or Jacobsen (2010), our data set includes both fatal and nonfatal accidents. Using unique vehicle identifiers (VINs), we determine the curb weight of each vehicle involved in an accident, thereby minimizing concerns about attenuation bias induced by measurement error. The rich set of vehicle, person, and accident observables in the data set allow us to minimize concerns about omitted variables bias. Using these data, we estimate the external effects of vehicle weight on fatalities and serious injuries conditional on a collision occurring.
Two key results emerge:
1. That vehicle weight is a critical determinant of fatalities in other vehicles involved in multi-vehicle collisions. The data implies that a 1,000 pound increase in striking vehicle weight raises the probability of a fatality in the struck vehicle by 47%. The authors then calculate that the total external costs of vehicle weight from fatalities alone are about $93 billion per year.
2. Second, light trucks significantly raise the probability of a fatality in the struck car – in addition to the effect of their already higher vehicle weight.
and 
. You can also watch it on 
“How many times have you been driving carefully on a snowy highway when someone in a big SUV comes barreling down the road at the speed limit or above.”
It’s much more exciting when you round a hairpin bend on a snowy mountain road to see the big SUV bearing down on you – sideways. Been there, done that, got the seat cleaned afterwards
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This is exactly how my friend’s wife lost her life. Someone who felt invincible in their mega-SUV whizzing around a hairpin turn like they were playing an xBox game.
their conclusion: I should volunteer to pack my family into a tiny light weight car instead of buying a comfortable 4wd minivan or SUV that will fit all of us comfortably and keep us safe.
altogether now:
http://youtu.be/MqTKZgEW8pM
Hot debate. What do you think?
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Comfort is subjective. I could no more feel comfortable in one of those SUVs than I could wearing those baggy waistband-below-the-crotch pants that seem to be the fashion among certain groups these days. But I was perfectly comfortable in the series of small cars I’ve owned (Austin-Healey, Jaguar, down to the more recent Honda CRX & Insight), and I do believe I could get comfortable in a Tesla, too.
Feel free to enjoy that comfort, but don’t get upset if you have to pay for the external costs your luxury is putting on the rest of us.
So you want to force me at gunpoint (which is what government does with laws, tax collecting, and its police power) to subsidize your free choice to drive a lighter, less-safe vehicle? Should all of us be required to drive Trabants or pay fines/taxes? Hmmm…that means a government enforced maximum of something like 2 kids, no room for camping gear, no towing a boat, no comfortable trip to see Grandma on the other coast, …no car-pooling with 6 kids (in only one vehicle) to sports or Scouts…You seem to want to control a great deal in my life at the expense of YOUR automotive choices.
PS: How ’bout if we tax people who CHOOSE to drive smaller, less safe cars because of their choices — likely to incur higher medical bills, rehab costs, disability payments…
PPS: mom of 5, grandma of 4; our family drives an smaller SUV, a minivan, and a full-sized pick-up.
Yes indeed, Chris. I do want you to pay for the choices you make which impact other peoples lives. At gunpoint, if necessary. If you want to live in the woods by yourself, go ahead. If you want to live with civilized people you pay your fair share (which might even include paying extra for schooling your oversized family).
The rest of your post is just nonsense. Do you really equate raising the price of overweight vehicles with a government limit on the number of children you can have? It sure doesn’t seem like you want anyone to take your post seriously.
Btw, the fact that I make a choice to not wear body armor every day doesn’t mean you should have the right to fire your handgun around randomly. That analogy will be lost on you, I’m sure.
This will drive you even crazier. The government is NOT adding an extra tax for behemoths.
At the same time the feds tell us they are raising mileage standards for cars, the giant SUV’s and trucks which kill, maim and waste gasoline have been given a special TAX break this year! (The current Pres. signed this into law. Thanks.)
The tax break applies to SUV’s and pickups that weigh AT LEAST 6000 pounds. Any “business” that buys one gets to depreciate it all at once instead of over 5 years for cars. A huge tax benefit that encourages them to buy the biggest and baddest vehicles.
So if that 6000+ pound vehicle tailgating you gets you upset, just remember you are paying for his right to tailgate by giving him a tax break. “Tax breaks” are paid for by other taxpayers–including those who are trying to do the right things by buying reasonably sized, good mileage cars.
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the modern prisoner’s dilemma
SUVs, of course, are the demon-vehicles of the eco-set, but forget them just for a minute. As I read the post, it’s mostly talking about relative vehicle weights, which apply as much to the difference between full-size and compact, or compact and sub-compact, or sub-compact and micro, or micro and motor-cycle for that matter. In all crashes involving vehicles of discrepant size, the safer one to be in is the larger, the less safe is the smaller, as has long been obvious. If we’re only looking at discrepant-size crashes, in other words, it’s not just the hated SUVs that are the problem, it’s anything heavier than a motor-cycle, or maybe a bicycle. If, on the other hand, we’re really interested in relative vehicle safety, then nothing that I can see in this study refutes the case that the heavier the safer. You want regulation for safety, then never mind “light trucks” — policy-makers should be “nudging” us all into big trucks.
This would only make sense if the ONLY goal was safety, i.e. that the cost of the vehicle and the fuel to power it were inconsequential.
So how much is a life worth, then? Whatever happened to that old refrain, “If it saves just one life…”?
But seriously, folks — look at the title of this post: “Killer cars: an extra 1000 lbs. increases crash fatalities by 47%”. Why not say exactly the same thing, but in this way: “Killer cars: a decrease of 1000 lbs. increases crash fatalities by 47%”? Hmm?
And the title is false or misleading in other ways too — as far as I can see, it says nothing about any decrease in crash fatalities that extra 1000 lbs. produces for the occupants of the heavier vehicle. I don’t have the figures, of course, but it’s at least possible that that decrease more than makes up for the opposite increase, meaning that the title would have to be something like, “Life-saving cars: an extra 1000 lbs. decreases net crash fatalities by x%”. Of course, as you imply, encouraging such heavier vehicles would only make sense if the lives saved were inconsequential.
Sorry, that last sentence should read: “… encouraging such heavier vehicles would only make sense if the lives saved were not inconsequential.”
That “old refrain” is only repeated by politicians with an agenda, not by anyone wishing to have a serious conversation (and certainly not here on the freakonomics blog).
Well, speaking of “agendas”, one might think that the obviously biased title of the post alone would be evidence of one, even here on the freakonomics blog. That doesn’t preclude having a serious conversation, but it does include outing the agenda (such as hostility toward the politically incorrect SUV).
There’s no obvious agenda in the title of the post; it may be a little sensational, but not much more so than the title of the paper itself –”Pounds that Kill…” Not every comment, article or study which criticizes SUVs should be dismissed as just political correctness.
Your argument is quite frankly as ludicrous as it is murky. Even in the unlikely event that more lives inside the large vehicles were saved that doesn’t nullify the external costs which the paper talks about.
The only reason those people are safer is because they are putting others at risk, if everyone needs to buy a larger vehicle to be safe then everyone is worse off. Many Americans who would prefer smaller cars choose not to since they would be at much greater risk because of all the other needlessly oversized cars on the road.
The bottom line is that if you want the extra safety that comes from having a larger vehicle you should be willing to pay others a fair price for the extra risk your safety is subjecting them to.
I think you need to reread this comment — the problem with the title isn’t that it’s sensational, it’s that it’s biased. And speaking of bias, I’d say your use of the word “ludicrous” is a good example of it, as is your notion of “the bottom line”. Here’s a more reasonable one — those deciding to take a risk with smaller vehicles shouldn’t expect to be paid for it.
Your previous comments do not show any bias in the study. At best they point out that this one single study does not examine every possible crash of every vehicle in every detail (no study could, which should be obvious). It does not mean that we should blindly ignore the results until we have studied every possible detail. Using your tactic we would have delayed requiring seat belts for another 10 years until we had studied the possibility that wearing seat belts didn’t encourage bad driving, or that wearing seat belts didn’t cause more deaths from long-term neck injuries etc. We may have more details and adjust our models later (e.g. add shoulder harnesses for adults, car seats for children), but the basic principle is sound: seat belts save lives (in general) and having needlessly large vehicles on the road takes lives (in general).
Do you seriously think more lives would be saved if everyone were just to add another 1,000 to their cars (or if we mandated a minimum 4,000 lb limit)? Do you think the cost of such a policy (materials, fuel, pollution, …) would be a reasonable price to pay for those lives?
Then please provide a reference to a study that indicates this, or we’ll just have to wait for someone of your mindset (who doesn’t have that politically correct bias) to do one. I think we’ll be waiting a long time.
Why are you reading this blog, Larry, if you don’t seem to understand the power (and sometimes brilliance) of such “freakonomic” studies? Is it just to combat those politically correct SUV bashers?
How about this; if a driver is convicted of vehicular manslaughter AND their vehicle class is larger than the victim’s it automatically becomes voluntary manslaughter. The order of severity goes involuntary, voluntary, murder, premeditated murder. This seems to me to be simple to apply and enforce without adding any new taxes or government oversight and can be done by the judge with normally available information during the trial.
I agree! So let’s increase the size and weight of the smaller vehicles to make the reletive difference smaller!
I think this whole study is silly. I agree with the poster who said we need to solve the reasons for accidents, not punish those of us who need larger vehicles for real reasons.
I think you missed the two interesting economics questions here.
First, this is a classic public goods question – heavier cars might create more fatalities but they are safer for their driver, who can transfer risk to other drivers. Since the driver is the decider on how many SUV’s are on the road, it’s a nice illustration of externalities.
Second, you put the blame on “heavy” when, logically, the blame lies with “inequalit.” If everybody drove SUV’s this damage would be mitigated, no? Meaning the blame also lies with small-car drivers, just as it would if they didn’t wear their seatbelts.
Except that you also need to include the externalities (and internalities, if that’s the right word) of such things as fuel consumption and driver attitude & involvement. Fuel consumption’s pretty obvious: I see it in action every month or so, when I put $20 worth of gas in the hybrid, and watch the SUV owners on the other pumps run up close to 3 figures – and know they’ll be back next week.
It’s the attitude thing that I think really causes the problems. SUVs and the like are so big that many of their drivers appear to believe that they’re exempt from all sorts of constraints, ranging from common courtesy to the laws of physics. They’re so insulated from the world that their drivers feel free to use them as mobile office, gossip fest, makeup parlor, and sometimes video game center.
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“There’s no reason you can’t add the taxes for the external costs of larger vehicles while still working to reduce the other risk factors.”
Just a thought, by your logic I could also tax smaller vehicle owners for putting themselves at more risk.
I drive a compact bc i don’t like buying gas, but I also don’t like social engineering via the tax code.
As addressed elsewhere, you certainly could add a tax which would encourage people to move to larger vehicles. This would probably (according to the study) makes us a little safer.
Is that really what you’re suggesting we do? I don’t think so.
If we can agree that having vastly differently sized cars is a bad thing, we should (as a society) try to minimize that danger, if possible. If we have to pick one size of car to encourage, should it be large cars or small cars?
This is not social engineering, it’s about making people pay for the external costs that result from their actions.
Sam: If we have to pick one size of car to encourage, should it be large cars or small cars?
For safety reasons, the answer is clear: large cars, the larger the better (since, as another commenter above noted, not all crashes are with other vehicles). Of course, for fuel economy reasons, small cars, the smaller the better. But then there’s the problem of people with families that won’t fit in small cars, so we’re back to large cars, unless, for reasons of over-population, we want (as a society) to discourage people from having families, except that maybe over-population isn’t as fashionable a worry as it used to be, and so…?
And we haven’t even touched on bumper height, design, or the color of cars yet, and which shades are statistically more likely to be killers. Those tax-assessing “encouragers” sure have their hands full. Maybe we as a society should just decree that one size (and color, design, etc.) should fit all, and have done.
“Larger is better” is just wishful thinking. Would you care to cite a study or article which indicates this?
The weight of a vehicle is not a plus in all accidents. It certainly can be if you’re say running into a mail box, but it won’t help much if you slam into a concrete retaining wall or roll down a hill. It is also a significant negative when accidents involve pedestrians. Finally, as another commenter pointed out, excess weight will actually cause more accidents since it reduces maneuverability (even ignoring the possible/probable more aggressive driving style of large vehicle drivers).
You keep intentionally conflating vehicle weight with other factors. Nobody is suggesting we strip out safety features just to save weight or that we limit vehicles to two passengers. Just that you can drive a 5,000 lb 6 person vehicle instead of a 6,000 lb 6 person vehicle. Or a 3,000 lb 4 seater instead of 4,000.
Is there a study which shows that a particular shade of car causes more fatalities to other drivers? If so, then I agree with you that we should account for that external cost as well by taxing those vehicles. If not, then your sidebar is just meaningless obfuscation.
“Larger is better” is just wishful thinking. Would you care to cite a study or article which indicates this?
I’ll leave that for you as an exercise, Sam. And then, for extra credit, you can cite a study or article which refutes it.
“…by your logic I could also tax smaller vehicle owners for putting themselves at more risk.”
No, because the small vehicle owners are not putting themselves at risk. They are being put at risk by people who choose to drive larger vehicles. That is, if Mister SUV buyer increases his safety by one unit by buying a vehicle that’s 1000 lbs heavier than it has to be, then he’d decreasing everyone else’s safety by 1.47 units.
Second, it seems a question of basic rights. People have the right to risk their own lives if they want: climb mountains, go skydiving without a parachute, eat a diet of Big Macs, whatever – it’s their choice. They don’t have the right to risk other people’s lives from ego, carelessness, or insecurity about the size of certain body parts.
Hot debate. What do you think?
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People have the right to risk their own lives if they want: climb mountains, go skydiving without a parachute, eat a diet of Big Macs, whatever – it’s their choice.
Or, they can drive a car that’s 1000 lbs lighter than it has to be, out of sanctimony, self-righteousness, moral preening, a smug sense of their own environmental piety, whatever — it’s their choice.
Hot debate. What do you think?
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No properly-designed car is ever lighter than it has to be, because if it was lighter, it would break. If it weighs more, then the excess weight could be removed, improving performance and/or fuel economy. Or in the words of Lotus designer Colin Chapman, “Simplify, then add lightness.”
On the other hand, sloppy design and/or appeals to insecure egos (e.g. current domestic pickup trucks) can easily add thousands of pounds of non-functional weight.
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No properly-designed car is ever lighter than it has to be, because if it was lighter, it would break.
Oh right. Just as no properly-designed car is ever heavier than it needs to be either, because if it were heavier it wouldn’t run. Please. You’re mixing up engineering limits within a given design choice with the design choice itself. And if it’s insecure egos you’re upset about, I think you’d be better off fretting over the efforts at conspicuous display of rectitude on the part of pious Prius drivers.
Larry, please. The Prius is not a small car, it’s a four-door sedan, officially classed as a mid-sized car, and pushing a ton and a half (2921 lbs curb weight). A small car is half the size, as for instance this one: http://en.wikipedia.org/wiki/Lotus_Europa
And rectitude is not the attitude one displays when driving such a car. Not at all
A carbon tax isn’t social engineering, and would address the size issue, as well as the pollution noted above. I drive a Dodge 3500 PU–since its a business vehicle, I can address the costs of a carbon tax through my pricing structure. Anyone who wants to drive a similar vehicle for pleasure can certainly afford to pay for the external costs they generate. Kill lots of birds with one stone…
Why is a carbon tax not social engineering, but an excessive weight tax would be? I don’t see a fundamental difference as they are both methods of paying for currently unpaid external costs.
I liked this paper better when Newton wrote it. Of course a vehicle that weighs 1000 lbs more than mine will be more likely to be fatal for me. The 47% figure is meaningless, unless someone can convince everyone to drive vehicles from within a thousand pound range.