A car safety group says passengers in the back seat need better seat belt systems.
David Harkey is President of the Insurance Institute for Highway Safety.
He says technology in the front restraint systems of newer model cars tightens the seat belt in the split second after a crash.
That keeps the person's body from moving forward too fast from the impact. The technology then allows the person's body to move forward as the air bag deploys.
This technology reduces the severity of injuries, says Harkey, but it's typically not part of rear seat belt systems, except in some luxury vehicles.
"We were seeing more severe injuries for those in the rear seat compared to those in the front seat," says Harkey, "and specifically what we were seeing were an increase in chest injuries."
Harkey says his group is considering adding a new test to see how well rear seat belts protect passengers.
He says improving rear seat safety is going to become ever more important, as more people ride in the back seat of Uber and Lyft vehicles.