Mercury 2009 Grand Marquis Owner's Manual page 155

WARNING: The appropriate loading capacity of your vehicle can
be limited either by volume capacity (how much space is
available) or by payload capacity (how much weight the vehicle should
carry). Once you have reached the maximum payload of your vehicle,
do not add more cargo, even if there is space available. Overloading or
improperly loading your vehicle can contribute to loss of vehicle
control and vehicle rollover.
Example only:
2009 Grand Marquis (grn)
Owners Guide, 1st Printing
USA (fus)
Tires, Wheels and Loading
155