Voice dial without Internet connection
Last time I checked hands-free voice dialing is not possible with Android.

http://code.google.com/p/android/issues/detail?id=9817

Put simply, Android is NOT car-friendly telephone. 

In fact, Android phones may be banned from use while driving in some states, as Android does not support hands-free operation.

Perhaps, nothing wrong with that if we consider it as just a small internet tablet and not demand full telephony capabilities from it.