Mercedes-Benz 2007 SL 55 AMG Operator's Manual page 117

Controls in detail
Locking and unlocking
Vehicles without KEYLESS-GO*
1 Trunk closing switch
Vehicles with KEYLESS-GO*
1 Trunk closing switch
116
Press trunk closing switch 1 briefly.
The trunk closes.
Closing trunk and locking vehicle from
outside (vehicles with KEYLESS-GO*)
In vehicles with trunk opening/closing sys-
tem* and KEYLESS-GO*, you can close the
trunk and lock the vehicle simultaneously
from the outside using the KEYLESS-GO
locking/closing switch.
1 KEYLESS-GO locking/closing switch
Make sure you have the SmartKey with
KEYLESS-GO with you.
Press switch 1 briefly.
With the doors closed, the locking
knobs in the doors move down and the
trunk starts to close automatically.
All turn signal lamps flash three times
to confirm locking once the trunk has
closed completely. The anti-theft alarm
system is activated.