Bytamin_c.com has a board that specializes in BCB. You could try there.
In general I would look for a push_back() or an insert() or an add() method within the class. STL vector class uses the push_back() method for routine use and insert() for special occassions.
#include "car.h" //depending how you set it up
TISArrayAsVector <car> cars;
temp.numWheels = 4;
temp.speed = 55;
cars.push_back(temp);//or as appropriate based on interface