Study Says Lighter, Smaller Cars Can Still Be Plenty Safe

When going to buy a car, most people instinctively think bigger equals safer. This is not necessarily the case, according to a report issued by the Rocky Mountain Institute.

The report, titled "Triple Safety," points out that cars have dynamic components, and it's not as simple as saying a lighter object will lose to a heavier object. Though the laws of physics would suggest this, cars are not simple objects. Equipped with structural advantages like crush zones that can absorb an impact, cars that make use of certain materials can be just as safe as their larger counterparts.

In addition, these small vehicles constructed with light-weight aluminum, other composite materials, or those forged with nanotechnology, can be lighter and more fuel efficient. As automakers move toward the new 2015 fuel economy goal, they'll have this concept in mind, but it's also important that consumers understand it as well.

Lighter Cars Promoted for Safety, Better Mileage (MarketWatch via Technoride)

Comments

[Marcus C.]

I drive an Explorer and have been hit twice in the past three years. Neither time did I suffer any injuries however in both cases the other driver/passengers did. The most advanced state of the art Civic or Focus does not stand a chance against a larger SUV. You can do all the "studies" you want, any normal person would much rather be in the larger vehicle.

[LM]

I guess I'm not "normal". I hate those behemoths. Plus, in a smaller, nimble car I can get away from people in unstable whales like yours.

[Spanky]

Marcus,

You're absolulely right. Though let's look at this from a different perspective. The other drivers might have been hurt worse because you drive an Explorer (I know it was their fault because they hit you, but let's say you were driving a Civic and got hit by an Expedition). I know this would never happen, but if we all drove smaller cars we'd all be on the same playing field. Then maybe we wouldn't have that guy that derives safety or power(you've seen him) from a huge truck with a lift kit that comes barrelling down on you on the interstate when you clearly have someone directly in front of you.

[Rob]

I would say just ban all these big cars, but with $4/gallon gas, chances are they will eventually just ban themselves.

How ironic that for years, it has been considered unacceptable to have reasonable gas taxes, but now our nation's decision to tax too little and spend too much has devalued the dollar to the point that oil now costs $120/barrel. So instead of an extra $2 gallon going into the treasury, it now goes to the Missle east, Rusiia, and Venezuela whuile we're stuck with a Ford Explorer in every other driveway.

[Adrock]

Even with rising gas prices, there are always going to be large vehicles on the road for businesses, trucking and large families. So while the chance of getting hit by a larger vehicle may decrease in the future, its not going to go away. What we smaller car lovers have to hope for is technological innovation in the form of new, strong (and lighter) materials and evolving manufacturing processes. I for one am excited about the possibilities.

[Mart]

Adrock, that fact remains in the rest of the world too. You think that in Europe they don't have juggernauts clogging up the roads everywhere you go? Of course they do, yet road fatalaties are not through the roof there.

I'm not sure of the relative fatality rate between here and say Germany or the UK but I'd imagine they aren't too far removed (even allowing for the smaller cars and generally higher speed limits there).

Personally I generally trust most small cars to be safe in 99% of collisions where I would expect to come out relatively unscathed. No, i wouldn't want to be hit in a Smart by an Expedition headon, but neither would I wanna get hit by an expedition in ANYTHING. But in most collisions between cars not driven by insecure, "p*nis-enhancment device" truck drivers (yes, that means YOU, Expedition owner), I wouldn't feel horribly threatened...

[J]

LM,

Damn! I guess I am abnormal person just like you! XD

[DL]

funny how people put so much stock in their own anecdotes. Marcus, i can tell you that for motor vehicle accidents, SUV's are disproportionately represented when drivers or passengers suffer significant injuries requiring surgery. why? cuz they ROLL OVER! the only other vehicle group overly represented are of course motorcycles.

protect yourself by always wearing your seatbelt, keep a safe distance from everyone else on the roads (cuz they all are such terrible drivers, remember), and don't drive under the influence.

accidents don't just fall out of the sky. it usually takes 2 people to hit each other. unless of course you were drinking or trying to answer your cellphone and that dang pole hit ya. what you choose to drive won't change that, Mini or Explorer

[ed]

I think these little things are probably okay for commuting, but you can't carry much or many people. Prius isn't that small, and has room in the back seat. Still, in a crash with a pickup or an SUV, the small car loses. Rollover is the problem with SUV, because people think they are cars.

[silver]

The small car does not lose in all cases. That only perpetuates a stereotype. If the small car is a BMW or Mercedes it may be even more safe than the explorer that you will get in an accident with. The bumper height and mass of an SUV do not make it an automatic killer in a car crash. Yes if you are both going head on at 50 miles an hour it is likely that the truck will drive right over the car because of it's higher ride height, but that is very atypical of an accident. Crash test studies are not conducted with an weight given to the lighter car. If they survive the crash test, they survive it as well as a larger vehicle does. Newer smaller cars, if designed properly can perform just as well as larger ones.

[Javier Rose]

Rob,
You wrote, "...our nation's decision to tax too little and spend too much has devalued the dollar to the point that oil now costs $120/barrel."

You are a prime example why my wife and I insist our kids get a private school education. To often my fellow Americans make statements that prove one thing. The lack of a basic education in how the local and global economies work.

[Red]

Look at side impact ratings for cars and you'll find that some small cars are better than larger vehicles. And they're all tested in the same way - the same size and weight sled hits all the vehicles that are tested. I was impressed to see that the Honda Fit protects you better in a side impact crash than the Mercury Grand Marquis. On the other hand, those who talk about the laws of physics are right under many circumstances. In the case of a small car hitting an Explorer head-on, there's no doubt which will come out worse.

[Silver]

I like what you say Red, but don't look at the physics of the situation too simply. The smaller car loses if it cannot absorb the impact or if it's structure collapses due to the impact. I don't know what makes it a winner or loser, based on whether the car is repairable or not, but I think the best measure is if the driver can walk away. I believe Honda's new frame (or unibody, but the basic structure of the car) is formed in a way to allow it to survive impacts that would have caused an older small car to be destroyed. How much so, I don't know haven't read into too much, but the idea is you can build it to survive, up to a point.

[Red]

Silver,
You are right. A well designed smaller car will sacrifice much of its structure to absorb the collision forces, hopefully while keeping the passenger cell intact. And today's small cars are worlds better for safety than the Datsuns and Pintos of the past.

[Tom]

All things being equal, a larger vehicle will do a better job of protecting you in an accident. I'd rather be sitting in an Explorer than an Accord (my current car) if I was to be involved in an accident. The best thing that can happen is for gas to get so high that it prices the Explorer's of the world out of the market. It would also be good if the tax sucking Dems & Cons got off their ass and passed tax rebates for people who buy gas efficient cars.

[Infosaur]

Another factor when compairing large vehicles to small is "deflection" or imparting a secondary vector on the smaller mass.

[J]

And remember, the heavier the vehicle, the harder it is to stop it. Foce = mass x acceleration.

So driving an Explorer is not really any safer than let's say a Focus.

[Drew Duplickson]

J posted: "And remember, the heavier the vehicle, the harder it is to stop it. Foce = mass x acceleration. So driving an Explorer is not really any safer than let's say a Focus."

Are you serious or just plain dumb? Last year I was struck going through an intersection by a another driver in a Ford Fusion. She later died while I walked away with bruises and a sprained ankle. At the time I was driving a Mercury Mountaineer. Both her and I were wearing seatbelts and as the police noted the difference was the size of the vehicles. Apparently she struck her head on the pillar while I did not.

Keep telling yourself that a larger vehicle is "not really any safer".

[Bloke]

While I don't agree with J, that harder to stop equals a less safe vehicle since that is a product of the brakes themselves and not necessarily the mass of the car, I cannot get over how many people make a rule out of one experience. There are so many things that happen when you crash only, the fact that you were driving a bigger vehicle is not the only or even the most prominent reason you were unharmed. The design of the vehicle (overall design and safety features), the place and speed of impact, the actual person's body type all come into play.

[J]

Drew Duplickson,

So who is the dumb one? Someone made their comment based on just one incident or someone made a comment based on proven physics law?

If you want to say that your experience is a better one, let me tell you this. Every single snow day on my way to school and back home, there are much more SUV in the ditch then cars. Ratio is approximately 6:1 while the SUV is 6 to cars 1.

Bloke,

I take it as you understand the Newton's second motion law. But you just don't like the fact that my car can stop much easier than your SUV and possibly changing its direction due to less inertia.

[Bloke]

J, what kind of SUV do I own? Are you sure you can stop in less distance? Have you ever seen what a Jeep Cherokee SRT8 or an Infiniti FX can do? They can rip past and slow down faster and shorter than many cars. And possibly changing its direction, well sure it's possibly easier, but is it really that way? Yeah there is more inertia with a bigger mass, but if the brakes are better it will stop it better. And if the center of gravity is lower or the suspension is set up the SUV can change lanes as good or better.

Don't get me wrong though, I like the fact that you drive a car over an SUV, and make a conscious effort of it. I hope you have been able to convince others that that is a good idea. I own a truck and a car and as far and as far as being safer, I have no idea. There are so many things that can happen out there, I think the best thing to do to be safe is to drive defensively and keep your cool.

[J]

Bloke,

Comparing a tuned SUV and a normal car is a fair comparison in your opinion?

[J]

In other words, when everything is equal, a car with lighter weight is easier to manuever than a SUV with heavier weight and higher center of gravity.

[Flash]

Two things to add:
Putting on my hat as a Firefighter, in our more rural area, we see a lot of single-car accidents, usually of the "I swerved to avoid a (add animal or delusion of your choice)" variety, but often due to ice, cell-phone use, or changing the radio. In these accidents, it is probably 9 SUVs or pick-up trucks to one car...the bozos in the cars simply can recover from their stupidity in time. In accidents involving two or more vehicles, and where at least one of the "participants" is usually an SUV or a pick-up truck, I observe that the damage is indeed usually worse on the smaller cars, and in fact the newer they are, the more they seem to "progressively crush", therefore taking out more of the structure, BUT the people in the cars usually seem to fare better as far as injuries. So take your choice: damage to your vehicle (cars) or to you (SUVs and trucks). I suspect a lot of that difference is due to design, not weight; unibody and crush-zones in the cars versus body-on-frame truck construction. The problem is, for an SUV or a pick-up truck to carry the weights expected and tow the loads expected, they need to be built heavier and (evidently) with body-on-frame construction, and with a higher center of gravity. My conclusion is, drive what you NEED (not what your ego wants?), for maneuverability, fuel economy, safety, and for whatever load you really expect to carry or tow, and learn and understand the limits of your vehicle's design and your skills. If you are not tall enough, get a booster seat! And NOTHING makes more of a difference in any accident than SEATBELT USE!
OK, second thing:
You want to see maneuverability comparisons? Go watch a few S.C.C.A. "Rally-Cross" (off-road) and "Auto-Cross" events! All of the top winning positions, indeed some whole classes, are DOMINATED by smaller cars, in the "stock" and "prepared" classes ("modifieds" and purpose-built race cars are another matter); smaller and lighter simply drives circles around bigger and heavier. Just watching the "All Wheel Drive" Rally-Cross class is a perfect lesson...the class is dominated by Subarus and the occasional Mitsubishi or other small car, then you see a Jeep Cherokee or a Dodge pick-up try their hand at it, and it looks like a hippopotamus trying to catch a cheetah.
But best of all, ENTER YOUR OWN CAR at one of these events, sit on your pride, and LEARN TO DRIVE! You will really learn how to handle the beast, maneuver around and evade obstacles, and you will be amazed at how much better a driver it will make you...no matter what you are driving. Then remember, everybody else out there driving really is trying to kill you...I am, anyway.

[Bubba Jones]

Sorrig geyes, I need them big oll tars an huge lift kit on my F-350 cauze them itty bitty craker boxs yall drive kept gettin hangd up under my picumup truck when I crall all over you,

[Bubba Jones]

Sorrig geyes, I need them big oll tars an huge lift kit on my F-350 cauze them itty bitty craker boxs yall drive kept gettin hangd up under my picumup truck when I crall all over you,

[Bloke]

J, if everything is equal how is the car lighter? What are you saying is equal? I am saying everything is not equal.

[Bloke]

J, here is a question for you also, what I am talking about is all based on this statement:

"And remember, the heavier the vehicle, the harder it is to stop it. Foce = mass x acceleration.

So driving an Explorer is not really any safer than let's say a Focus."

So what is happening if the vehicle is not accelerating, how much Force does that vehicle have?

[J]

Bloke,
Your last comment shows how little you know about Physics.
So I would save my time from educating you any further.
BTW, you do not even understand what did I mean by everything equal, which means the brakes, tires, etc. But the weight will NOT be the same.

[Bloke]

J, what is the problem can't you answer the question? That's right, answer it first and then you can comment about what I know about physics.

[Bloke]

"BTW, you do not even understand what did I mean by everything equal, which means the brakes, tires, etc. But the weight will NOT be the same."

How can I understand you, when you use garbled language? Take a breath, type it out, check your spelling, you're almost there...