Does anyone know whether or not "electronic" car keys are banned?

The New York Times reported on Friday, August 11 (See Graphic Accompanying This Article) that British airports had banned carrying on "electronic key fobs."

My car, a Mercedes Benz, has an electronic key which consists of a chip that starts the ignition and four buttons to open and close the doors and trunk and sound the alarm. Although in previous model years there was a non-electronic substitute for this (it didn't have the remote functions), that has been discontinued.

I know that the Cadillac STS, for example, has a key ring "fob" which is used for the keyless ignition.

Are items such as these banned from US flag carriers? If so, it will make it extremely difficult for people like me to drive to the airport if travelling with only a briefcase (e.g. flying LGA-DCA-LGA via the DL Shuttle for a meeting) as I won't be able to take my car key with me.

The TSA Website is not at all clear on this question.

All replies appreciated.