Last week, the Defense Advanced Research Projects Agency unveiled the Ground-X Vehicle Technology program, which invites contractors to help design a radically different fighting machine. DARPA's goals for the program couldn't be more radical: it wants a vehicle that's twice as fast as what U.S. armed forces use now, that weighs half as much (with a corresponding reduction in fuel use), takes only half the crew and can travel over 95 percent of terrain.

DARPA says the "more armor" design of modern vehicles has now reached the point of diminishing returns. Such trucks cost millions more to design, build and run, need long supply chains of fuel and parts and are so heavy they can't stray far off roads making them hard to deploy rapidly into trouble spots.