All I have to say in response to this article is DUH!!!!!! DUH DUH DUH DUH DUH DUH DUH!!!! Are you seriously stupid? "Uhh, I wonder which will win when we make them hit each other head on?" Oh, shocker, the bigger one. They are both cars from the same year, so the same technology was used in that same plant to design those cars.

This test is the equivalent of saying, "Hmm, I wonder who punches harder, a heavyweight boxer, or a lightweight boxer?" Well duh (all things equal for the sake of argument), the heavyweight is going to punch harder because they both trained to punch as hard and fast as they can, except the heavyweight has more mass. There is no question about that, it is blatantly obvious even to a young child. HOWEVER, that does not mean that the heavyweight will win if they were to compete with each other.

Can you image how stupid someone would have to be to buy into this? "Oh ****, the tiny car I bought doesn't stop cars twice it's size. If I had known that before..." Seriously, anybody who sees/reads/hears this story and gets scared and thinks they need to buy something bigger is a complete idiot, not capable of anything approaching complex thought. He or she needs to just go buy an Excursion and have fun parallel parking.

 

I don't think smaller cars are less safe...in a collision perhaps, but overall safety? If you drive the car in an alert fashion and with good feedback from the car, I'd say this is a big part of safety. In this case a small car might very well win out. Equating a crash test with overall safety is not altogether accurate.

 

EXACTLY!!! Somehow, we seem to be the only people that realize this. People that drive small cars that is.

 

Sorry, COKen, but you are referring to Newtonian kinetic energy, vis a vis inertia. The quoted formula defines the amount of energy equivalent when mass is converted to energy, as in a nuclear reaction. I'm very hopeful that no automobiles have mass which becomes energy in that context (a MINI, fully converted to energy, could wipe out a good part of the northeast).

 

I have to agree. That crazy old bird Issaic could walk into any final exam with nothing more on his crib sheet than F=ma (Force = mass x acceleration) and derive any equation of motion he wanted from it. What a curve-breaker he was...

Since acceleration is the change in velocity per unit time (dv/dt), then the sum of all forces is just (m)(dv/dt). Momentum (P) is defined as mass x velocity (mv), and so by definition the sum of all forces becomes the change in momentum over time (dP/dt).

The cool thing about momentum is that in a linear, closed system (like a car crash, taking some liberties in ignoring friction, etc. and calling it elastic) it is conserved: m1u1 + m2u2 = m1v1 + m2v2 (u is velocity prior to crash, v is velocity after the crash).

So it all boils down to how big (heavy) you are compared to the other guy, and how fast you were each going when you plowed into each other.

 

As you can see, I'm not a physicist. I really intended to say what Gil-galad said, but he beat me to it.

 

True, up to a point. The safety for the passengers also depends upon the distance between the front of the car and the passenger compartment and how well the engineers have designed the engine compartment to absorb the energy upon impact.

While the collision scenarios are extreme they do happen in the real world (either front or side) at intersections. The collision between the Camry and Yaris was particularly gruesome IMO. Its too bad they didn't show how the Mini held up against another car, e.g., Honda or Camry. The Mini is fairly heavy for its size.

 

I also would have liked to see this, but I expect that it didn't fit into their agenda.

As others have said, this is just one part of an accident. They would need to add in a lot of additional variables to get a real world picture. I would like to see, in addition to survivability when a crash happens, how good various cars are at avoiding the crash in the first place, but then you would also need to include the driver's skills, driver attention, etc.

 

If they are basing their statistics on claims, fine....but surely thousands of collisions are avoided altogether every day because of car maneuverability. In this case a small, nible car would be an advantage, even though it may not register in available statistics.

 

The thing about statistics is you can manipulate the data to say virtually anything you want. For this the manipulated it so the heaviest car went against the lightest car from the same manufacturer head on with no other variables. guess what, mass wins. They could have done a MINI vs a 7 series as technically they are the same company (same as Smart and Mercedes). And for all we know they did but it did not give the results they were looking for. So always take statistics with a grain of salt.

 

How about a Mini vs. a Tahoe?

 

Exactly! I don't know how often nimble handling has gotten me out of a sticky spot. While test like this show that small cars don't have the mass of larger cars they don't take into consideration all the other factors namely accident avoidance:

Handling
Breaking
Traction control
Driver skill

 

The MINI's crumple zones look to have worked as engineered. The Tahoe looks to have succumbed to top heaviness/unstablity; a big problem with many truck based SUVs.

 

Well, in truth they did not crash the heaviest car in the manufacturer's lineup against the lightest car in the lineup. For example, the Mercedes C class is far from being the heaviest car made by Mercedes Benz. They crashed a mid size or full size car against a mini sized car. The results are not surprising. But I don't think the comparison is manipulated or misleading. The Camry, Accord and Mercedes C class are all cars that are commonly found on the road in my area. So, a collision between any of these cars and a mini car is not at all improbable. Someone interested in a small car may decide based upon the film clip that they would be willing to trade a few mpg to get a slightly larger/heavier car. I certainly would not let a teenager drive a mini car for precisely the reasons cited in this report. They can learn to drive a tank like I had to. How about one of those old Volvo 240s - it weighed 2 tons and had an 80hp engine!

 

While a "mini" car has its disadvantages, I wouldn't go the extreme opposite direction either ("big and old for the sake of big and old"). Automakers know a lot more about crumple zones and energy dissipation now than they did 20-30 years ago. A older Volvo 240 would still be an excellent choice, though, because Volvo was ahead of its time with safety considerations in those cars. But something like a 1978 Ford LTD might not be a good of a choice for a "tank", because without designed-in crumple zones, any collision forces and deceleration will be transferred directly to the driver/passengers. The LTD might not take much damage in a collision, but the occupants likely wouldn't fare as well.

 

Actually, two vehicle colliding head-on while both are traveling 40 MPH is not the same as a single vehicle hitting an immobile barricade at 80 MPH. The 80 MPH collision with a barricade is going to be *much* worse, because all of the collision forces are going to be absorbed by one car. In the two-car collision, the crumple zones and other deformation in *both* cars will help dissipate the collision energy. Think of it like this - would you rather hit a brick wall at 80 MPH, or hit a parked car that's resting against a brick wall at 80 MPH? You'd want the parked car as a buffer between you and the wall, because "smushing" the parked car in addition to your own will dissipate that much more of your energy over a longer period of time compared to just hitting the brick wall.

The two-vehicle collision starts to look even more attractive if you're in the heavier of the two vehicles. I would much rather have a 40 MPH/40 MPH head-on collision with me in a car and the other person on a motorcycle compared to me in a car hitting an immobile barricade at 80 MPH.

 

The comparison wasn't misleading or manipulated but by doing what they did they practically guaranteed the outcome. In that kind of crash heavy will win out. And ok, crash the MINI vs the 5 series or even 3 series.

 

Drive a heavy old car doesn't help. Most latest generation cars are so much stiffer than those old generation cars regardless of brand, in a head-on collision these new cars will simply cut the whole front off those old vehicles. (As shown in two head-on crash videos by fifth gear).

A safe bet for teenager driver: take the heaviest new generation car with reasonable handling + stationary crash test rating, and pay more at the pump.

 

Very true...MINI driving dynamics have gotten me through many, many potential mishaps, often several in a single day!!!

 

I agree, very true. I once had a large office chair fall off a truck and land right in front of me. The Mini nimbally avoided it. In my CR-V or wife's Accord, I would have plowed right over it.

I response to the test, I was taught in a defensive driving school (to avoid points for a speeding ticket! ) that if faced with a potential head on collision like someone passing on a two lane road) your best bet is to just drive off the road even if it means hitting a tree, wall or other obstacle. Physics is physics, since energy is proportional to the square of velocity a 40 mph head on collsion with an object travelling 40 mph toward you is four times more energetic than a 40 mph collision with a stationary object (neglecting energy absorption by the object you collide with.)

 

COKen,

Just to clarify: "As you can see, I'm not a physicist."

Nor am I...I've never taken a physics class. In fact, the only time I ever studied e=mc^2 was in 8th grade general science class.

My first comment was in response to Ryephile's remark about "all high school graduates should already know as common sense". I agree, but I'm afraid not many do, who have graduated in the last 20 years or so.

 

Good advice, although a two-car collision (equal masses and speeds) is only twice as energetic as a car/tree collision, not four times as energetic.

Compare total kinetic energies:

car/car: (both cars of mass 'm' and speed 'v')

1/2 m*v^2 + 1/2 m*v^2 = m*v^2

car/tree: (same 'm' and 'v' for the car, and v=0 for the tree)

1/2 m*v^2 + 0 = 1/2 m*v^2

 

The point is, there may be more energy, but a concrete barrier or a tree doesn't absorb much of the energy--most of the energy is transferred through the vehicle. So given the choice of a collision with an oncoming car, with me going 30 kmph and the other vehicle going 30 kmph, I'd choose that over a collision with a tree with me going 60 kmph. Same system energy, but the energy is dispersed through both cars in the head-on collision, whereas the energy is mostly dispersed through my car (and me!) in a collision with a tree.

Unfortunately, while some call this test the IIHS did "unfair"--the point is not to compare the results with a crash of the same small car with a barrier, but to point out the difference in crash performance of smaller and larger vehicles.

The same test, conducted with, say, two Camries, would likely have a much less shocking result.

 

Both systems don't have the same total energy, though. A single car going 60 kph has twice the total kinetic energy of two cars going 30 kph. That's why you'd rather hit another car with both of you doing 30 than hit a tree doing 60.

 

I hope your not serious. If so, you're an idiot.