I was so Wrong in thinking that the car was a converted Australian Holden !!
In fact, the first Kitt was a 1982 Pontiac Trans Am, and the second KITT, a 2008-2009 Ford Shelby GT500KR.
So maybe the first car was a Holden after all, as both Holden and Pontiac are manufactured by GM.

The voice file works nicely after unlocking as per post #8.