You are right - I have the same problem - for a few key numbers I used speed dial and I put in some pauses - so you can speed dial while driving, you don't have to be stopped to access the speed dial. I find myself calling companies and having to go to the receptionist to dial the extension numbers as I cannot do it while driving on the car screen.
So add some speed calls with the extension. Otherwise - yes you have to pick up the phone which is unsafe.
One thing - I had programmed the voice for my voice mail in the Black Berry with all the login and passwords etc. The car phone (Prius 08) doesn't have the capability for all those digits. (for direct access to the voice mail). One thing I like about this BlueTooth Hands freee - when people call me - it is great and very safe.