Probably not. As far as I know, they're still developing this technology and it's not available on the market just yet.
I played with Siri a bit in my Gen II on the new iPhone 5 today (iOS 6.0). It was sort of hit and miss. She sometimes came over the car speaker and I could talk to her and she'd answer me, other times it would "take over" the speaker for a bit, but I'd never hear her speak. I need to play with it a bit more to see if I was just being too impatient to let it come over the speaker or what.
Maybe in the near future, we can teach Siri to drive our Prius for us. That would be really cool. "Look Ma, no hands on the steering wheel". This could also help deal with the increasing problem with texting while driving and drunk driving. DBCassidy