nope, still not working. engine shuts down every time...

here's my code:::

// add world geometry
n_world = ent_create("newton_playground.mdl", nullvector, NULL);
n_world->flags |= FLAG8; // flag8 -> will be added to world collision geometry

newton_start();
on_close = quit;
on_space = drop_it;

const float updir[3] = {0.0, 0.0, 9.8};

car = ent_create("car.mdl", vector(100,200,500), NULL);
NewtonBody *car_body = newton_addentity(car, 80, NEWTON_CONVEXHULL, onforceandtorque);
car_joint = NewtonConstraintCreateVehicle (n_world, &updir[0], car_body);