If you're talking about carbon and chrome steels, not so much. They only contain fractional percentages of those elements. If it were stainless, the significant amount of nickel and chromium would definitely affect the weight. But since Chromium weighs less and Nickel weighs more, it would pretty much balance out. In short, if a six foot diameter wrecking ball hits your car, whether it was mild steel, CrMo, stainless, D2 tool steel or whatever, you still have pretty much the same problem.