While the center of the back seat is statistically the safest place in the vehicle (because you can never take a direct impact there), it might not always be the best place to ride, depending on which type of seat belt it has. If the center has only a lap belt (no shoulder belt), it would not be the safest place for an adult or a child using a booster seat. These people are better served with a shoulder-and-lap belt that can offer upper body restraint not found in a lap-only belt.
A child in a rear or forward-facing car seat can ride very safely with a lap-only belt because they have the car seat’s harness to offer upper body restraint.
Now that all vehicles, including taxis, 2008 and newer have shoulder belts in all seating positions, where someone sits is no longer as much of an issue.
Emily sitting on side as center lacks adequate head restraints. Her son is riding in a Graco Snug Ride 35 Classic Connect
Adults need whiplash protection – which means they need the vehicle seat or head rest to support up to at least the top of their ears. In many cases the head rest in the center seat is absent or too short for the adult – so in this case, the adult should ride on the side.