If you lock your keys in your car, just call someone on your cell phone who has your spare remote.
Hold your cell phone about a foot away from your car door and have the other person, who has your spare remote, press the unlock button holding it near the phone on their end.
Presto! Your car will unlock. Distance is no problem. Will work for the trunk also.
P.S. For some odd reason, won't work on non-SC vehicles.