My previous car was a 1998 Cavalier coupe. The plastic broke on one of the keys leaving a flat, thin key. I put this key in my wallet as a spare in case I ever locked myself out of my car. I read something about the HHR key having some sort of electronic device in the key itself. Is this true? Or can I remove the plastic part of the key and have a flat key to keep in my wallet?

 

HHR's use transponder equipped keys, with the transponder embedded in the plastic key head.

So removing the plastic will destroy the transponder leaving you with a key that will open the driver's door, but except for that, it would be useless.

 

I carry an all plastic emergency key for each of my cars. They will let me in if the car is locked and the regular key is not around.

The one for the HHR will even start the car but it dies in a few seconds.

My daughter somehow managed to snap off the metal part of the key for our '05 Neon and for a while I had just the plastic part stuffed in the plastic dash parts under the steering column.

With the key head close to the anti theft ring any key, including my plastic one would start the car and you could drive it anywhere no problems.

As time passed somehow the key head got dislodged and evidently fell out and got discarded. Now you have to use a regular transponder key to make the car go.