There's been multiple times for me while driving and I need to write something down. Except you can't because you're driving. Why not push a button on the steering wheel or command center. This would then pause any radio/music use. Have the radio dash read recording...then create your memo. Once your car is off, go through a process to sync this to your mobile and there you have your electronic post it note on your phone as a text message or which ever it may be.