the new voice search from google has voice calling. you have to press the voice search icon on the phone and say call (name). it goes beyond that as well: navigate to, map of, listen to, send message to, note to self, among others
I have bluetooth in my vehicle as well, but I have my Droid mounted to my windshield so I can listen to music too. I think even though bluetooth is enabled I think the mic on the phone is the only one that works for the voice search. I could be wrong as I haven't tested that out. press the voice search icon and say call (name) and see if it works for you while in your Toyota