What about the internal organs of people in big cars? IIRC, a long time ago, after a serious collision, paramedics were at first puzzled as to why the seemingly unharmed person behind the wheel was dead. Later it turned out that their internal organs had been ripped out of their arteries because big cars have/have much worse impact zones than smaller cars.
You have that story confused or backwards. Occasionally vehicle crash victims will suffer such internal injuries, mainly the elderly who already have weak blood vessels. But big cars don't have worse crumple zones, rather the opposite.
It's not "heavier vehicles", it's trucks. A lot of pickup trucks (and the SUVs based on them) were designed to prioritize load carrying capacity over occupant safety and have worse safety features than other passenger vehicles despite being heavier, and it turns out that matters.
