[EricH]

How about this one: something similar to the Grand Challenge, but at certain points, you have to stop and put x number of projectiles (say, rifle or machine gun bullets) into a target. Said target may be anywhere off or on the road, and a human is in the area to replace it or move it. Reloads must be autonomous and the vehicle must have said weapon inside, but not break a window.

Oh, and the X Prize was not done by DARPA. If I remember correctly, it was done by the X Foundation, or someone with a similar name.