Took plastic key attached a small loop of poly cord.. I wedged it between the front bumper. under car. 2 years ago. When needed pull on cord and key appears.
Used it twice.
Never moves and now everyone knows where my key is.

 

If you hide it under your car, you can easily open the top of the plastic key and remove the transponder chip.

That way, the key will get you in the car, but won't start it. Just in case someone finds it, they can't drive away with it.