On the Sonic and Spark it definitely can't. There's a separate app that can (BringGo) and although it's maps aren't bad they definitely aren't up to the level of Google's (or maybe even Apple's). They're about of the quality of most in-dash navigation system.
There's nothing built in to the Siri "eyes-free" system to support displaying data on an external display.
That's frustrating - it seems I have to pay the vehicle maker extra for inferior navigation then. I'm not sure why eyes free couldn't have used some form of AirPlay over Bluetooth to display apple maps
That would allow me to say things like "take me to john's house" which the in car system will likely fail to do even if it has access to my contacts
I guess siri will give audio directions though, lets hope...