FORD 2003 Crown Victoria v.1 - Manual (Page 121)

If the booster seat slides on the vehicle seat, placing a rubberized mesh
sold as shelf or carpet liner under the booster seat may improve this
condition.
The importance of shoulder belts
Using a booster without a shoulder belt increases the risk of a child’s
head hitting a hard surface in a collision. For this reason, you should
never use a booster seat with a lap belt only. It is best to use a booster
seat with lap/shoulder belts in the back seat- the safest place for children
to ride.
Follow all instructions provided by the manufacturer of the
booster seat.
Never put the shoulder belt under a child’s arm or behind the
back because it eliminates the protection for the upper part of
the body and may increase the risk of injury or death in a collision.
Never use pillows, books, or towels to boost a child. They can
slide around and increase the likelihood of injury or death in a
collision.
SAFETY SEATS FOR CHILDREN
Child and infant or child safety seats
Use a safety seat that is recommended for the size and weight of the
child. Carefully follow all of the manufacturer’s instructions with the
safety seat you put in your vehicle. If you do not install and use the
safety seat properly, the child may be injured in a sudden stop or
collision.
Seating and Safety Restraints
121