and who is going to drive it? Just considering their age...
Well, driving a tank is probably like driving any diesel truck. Realistically, I wouldn't be surprised if the tankery girls get some kind of unique probationary license for participating in competitions or something.
Just remember, Naomi and Alisa of Saunders are able to fly the C-5M Super Galaxy, and as far as we know, the School Ships are manned by the students, so i think driving and getting the license for a car is easier for them (Remember the Anzio Trio at the end of the movie).