Yeah, well, there's a really good reason that cars are made of that stuff. Don't be scared about what little your car is made of; chances are, it's trying to protect you (the driver and passenger) from harm when there is a crash.
When you look at a car crash on the news - particularly a front-on one - you'd think "Fuck, me." You should think "The newsreader's a dipshit. He's not 'lucky to be alive'. He's alive because of the awesomely awesome design of that car." Indeed, cars are designed to be tough, but soft. Reason? It involves a little physics. Take a seat. Have a marshmallow. Let me explain.
In physics terms, they're designed to have a large crumple zone so that the stopping force is spread out over as much time as possible, causing minimal damage to the occupants (although making for a really rotten-looking car afterwards). In non-physics terms, it's the same as jumping out of a tree or off a roof. If you land while bending your knees, it doesn't hurt as much as if you'd landed with your legs straight. You've probably also done some damage to those there legs.
This can also be explained in terms of George Of The Jungle. He hits so many trees that he should probably be dead by now, becase he has a huge stopping force all in one micro-second. If he hit rubber trees, he's be slightly safer as the rubber would provide the same stopping force over a longer period of time.
Even if you're skiing (which was the analogy I learned when I learned about stopping forces), one can slow down with minimal harm if one simply sits down and stops the skis touching the snow. However, one gets more than a sharp pain if one follow's George's idea of crashing into a tree.
So having your car made of those light, inexpensive, easily broken materials means that not only are production costs lowered, but you, the driver, are a lot safer than if it were rock solid.