As cars get lighter, the study reports, their death rates per million go up in two-vehicle crashes. But light cars also have the highest death rates per million in single-vehicle crashes."The same is true for utility vehicles and pickups," says the IIHS, "the lighter they are, the higher their occupant death rates. This is dramatically true for the very lightest utility vehicles and pickups."
Within weight classes, the study reports, cars have lower overall occupant death rates than utility vehicles or pickups, "mainly because cars have much lower death raes in single-vehicle crashes."
Boiled down, the best advise in this study for consumers concerned about safety would seem to be as heavy a car as they can get, particularly if it's a recent model with the latest safety considerations.
There are changes that car companies can put into their vehicles over time, but that's a long-term affect that won't show up for years.