Fuel-efficient technologies, such as hybrid engines, have improved, but they only will reduce fuel consumption by moderate amounts, experts said. FCS units, like today’s brigades, will require a substantial logistics re-supply tail of fuel and ammunition...
On the weaponry side, the mainstay of FCS will be cannons and missiles. These weapons will be more sophisticated than current systems, but not a major departure. Non-kinetic technologies, such as lasers and high-powered microwaves, are progressing, but are not expected to be ready for operational use for many years...
For survivability, it remains unclear what technologies FCS will employ. Conventional passive armor is out of the question if the Army wants to keep the weight of the vehicles at less than 20 tons. “We haven’t found magic armor,” the program official said. The most promising technologies so far are electromagnetic armor and active protection systems, which sense and defeat incoming rockets or missiles by deflecting or intercepting them... [But], according to several sources, there is a strong cultural bias in the U.S. Army against installing active defenses on vehicles, because they are perceived as unsafe...
The Army’s top acquisition official, Lt. Gen. Joseph L. Yakovac, acknowledged that much uncertainty remains as to whether FCS can deliver what it promises.
“I’m not clairvoyant,” he told reporters. “As we look at the technology, it may or may not mature at the rate we need.”
The current program is only a reflection of “the best guess today...”
Nevertheless, the Army has made a major financial commitment to FCS, increasing its overall estimated cost from $90 billion to about $115 billion, which will cover the entire 17 systems and a command-and-control network, to be fielded to possibly 43 brigades by 2025.
Back in 1999, when the Army launched 
