There's some data on that here [1] - page 19. It depends on the exact age range. For everybody under 45 the leading cause of death is unintentional injury by a wide margin. It's unclear what percent of that would be car crashes. Cancer and other stuff catches up pretty quickly in the 45-54 age range and becomes overwhelmingly dominant by the 55+ group. So it depends on exactly what age range we're talking about.
