It depends also on the type of crash and where the impact is located. Sometimes a smaller car ends up with better results and sometimes the extra weight of a large car creates additional momentum which is a negative factor - but not always. There's no set rule here, except to say that cars are much safer now than ever before. Crumple zones on either end of a reinforced passenger compartment is standard on all cars ans is the single best innovation for reducing injuries. Any more, the size and weight of a car has little bearing in how safe it is. Even a $14,000 Kia Spectra has the highest (1 thru 4) safety rating, proving that a car's size and cost have no bearing on how safe it is.