Possibly we will be allowed to question her over there and if there is a case to answer she might be tried in absentia and possibly allowed to serve sentence in the us
I don't know what the courts would normally decide in a case like this, presuming not drunk or speeding, but made a driving...
Heard on radio 5 that there was a case last year in the states where a georgian diplomat caused fatalities in a road accident when drunk driving. The US requested diplomatic immunity to be waived and Georgia agreed. So there is clear precedent here.
Apparently UK have done the same on occasion...