Cadillac 2009 XLR Owner's Manual page 45

Driver Side shown, Passenger Side similar
The seat-mounted side impact airbags for the driver and
right front passenger are in the side of the seatbacks
closest to the door.
CAUTION:
{
If something is between an occupant and an
airbag, the airbag might not inflate properly or it
might force the object into that person causing
severe injury or even death. The path of an
inflating airbag must be kept clear. Do not put
anything between an occupant and an airbag,
and do not attach or put anything on the steering
wheel hub or on or near any other airbag
covering.
Do not use seat accessories that block the
inflation path of a seat-mounted side impact
airbag.
1-41