MagicMT said:
So.. wouldn't it be more cost effective to make cars lighter (less materials?) but also stronger?
Nope. Look at Ferrari and Lamborghini. Thier cars are made out of lots of carbon fiber, aluminum, kevlar, all sorts of strong, light stuff, to keep the weight down. They are still pretty heavy cars (new Lambo Murcielago: curb weight-4020lbs

), but they have big, heavy, engines, and more and more of them (like the Murcielago) are going to AWD for extra grip, but also adding weight. But can you imagine how much that thing would weigh if it was all steel? But those composite peices are very expensive, so the cost is going to be very high, negating the benefits of using them extensively in mass-produced consumer cars. Plus, it's much cheaper to get a steel fender fixed than a carbon fiber fender.