College kids gave Siri new powers and now you can too This siri hack video features a command to unlock a (dirty) Tesla. I'd assume Apple will include functionality like this in the next siri update (especially since cortana can launch apps)
Limited to unlock, lock and honk.. I tried to see if there were additional commands that could be programmed, but I don't think so. It appears you cannot add additional commands.
They're pretty new to the game, so give them some time (and maybe some motivation by requesting it) and I bet they'll add more functionality. They probably didn't want to go too far without an official API from Tesla. - - - Updated - - - Also, looks like you can set up custom replies with a "respondWithOpenURL(url)" redirect for advanced PHP, Python, etc.
Yeah, this is what I was going to say. You could easily build your own functionality in. Many folks have already documented the Tesla API, so shouldn't be too hard to roll your own (if you choose to). I mainly posted it as I thought it was cool they used a Model S to demo.