What vehicle seat belt systems are unsafe to use with this car seat?

Do not use lap belts with emergency locking retractor (ELR), combination lap/shoulder belts with retractor, passive restraints mounted on the door, motorized shoulder belts, or lap belts forward of the seat crease. These systems cannot hold the car seat tightly at all times and are not safe for use. Consult your vehicle owner's manual if unsure. (Page 12-13)