Safety Vs. Fuel Efficiency: Are Automakers Willing To Sacrifice One For The Other?

In the movie Back to the Future Part II, there’s a great little exchange between the time traveling Marty Mcfly and his mentor Doc Brown. While traveling in a flying car and trying to stop the villainous Biff in the year 1955, Marty suggests that they attempt to cripple his car by landing theirs on top of it. To this suggestion, Doc Brown responds: “Marty, he’s in a ’46 Ford, we’re in a DeLorean. He’d rip through us like we were tin foil.”


It’s true, cars of the past were made of sterner stuff than they are now. A bump that wouldn’t bruise a peach will crumple a modern automobile’s side door like a piece of paper. This is because modern cars aren’t made out of the same materials as older models. The original Model T Ford had a body that was constructed out of a vanadium/steel alloy. Cars that are manufactured today are made out of aluminum or even plastic. So, if your vehicle is involved in a collision, then there’s a good chance that it’s going to end up taking extensive damage.

So why do car manufacturers use such weak materials? Well, there are a couple of reasons: One is that weaker, more crumple-prone bodies can actually protect you in an accident. Without getting too much into the physics behind it, when your car comes into contact with something, its momentum turns into energy. That energy needs to go somewhere. So, lighter materials are used because they will crumple, absorbing much of the energy in the process. If your car were made out of wrought iron, slamming into a wall at 60 mph would send a lot of that energy scurrying around looking for something into which it could be absorbed and dissipated. The natural shock absorbers (intervertebral disks) in your spine would take a massive hit, and you might find yourself paralyzed or worse.

But there’s another reason that car makers have been leaning more toward lighter materials: fuel efficiency.

Heavy cars, or more accurately, car with more mass, will require more energy to get moving. So, lighter cars (like the ones made out of plastic) will be able to use less fuel. This has lead to a concern among several groups. After all, if you take another look at the physics involved, you’ll see that when two objects collide, the one with less mass will absorb more of the energy.

But the issue isn’t as simple as that. Car accidents involve countless unforeseeable variables, and as we’ve mentioned above, sometimes a weaker car means a better protected driver.

So what does the future hold? That’s anybody’s guess. But with the likelihood of new laws aimed at raising the Corporate Average Fuel Economy (CAFE) soon being passed, you can bet that designers are coming up with innovative ways to get more miles to the gallon. The amazing thing is that not all of these new designs sacrifice your safety. Some of the more interesting ideas focus more on cutting down on wind resistance, or improving engine efficiency without reducing any of the car’s overall weight or size. However, some manufacturers are looking for the easy way out, and that means overall quality and safety might still take a hit.

So, the question is: Are automakers sacrificing your safety for better fuel economy? The only answer we can give is maybe. A giant car doesn’t necessarily mean a safer ride, however, and collisions will always be dangerous. The only real way to remain safe while driving is to practice safe driving (and that means never intentionally landing your flying time machine on someone else’s car).

Sladen West is a freelance writer dedicated to helping others stay safe through auto safety and defensive driving.

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