I HAVE A 3 SEATER, DURING A REAR END COLLISION, THE MIDDLE SEAT SWUNG BACK AND LOCKED WITH THE 3RD SEAT. WHEN THE SEAT LOCKS THERE IS NO SPACE BETWEEN THE SEATS; IF SOME IS SITTING IN THE BACK THE LEGS WILL BE CRUSH DURING A COLLISION. MY 5 YEAR OLD GRANDDAUGHTER WAS SEATING IN HER CAR SEAT AND BY A BLESSING OF GOD, SHE WAS ABLE TO RAISE HER LEGS BECAUSE THEY ARE SHORT. THE MIDDLE SEAT IS NOT PROPERLY LOCKED.