This recent article from National Defense Magazine stresses a point that's important to remember: real fuel efficiency gains in DOD systems are waiting out in the future somewhere. There's simply no way to wave a magic wand over an M-1 Abrams main battle tank or Bradley APC, which get approximately .5 and 1.7 mpg respectively, and get a big boost in efficiency. That these vehicles consume massive amounts of fuel is no surprise, as fuel efficiency (or productivity, as the Army likes to say) has never been a key performance parameter (KPP) during the requirements definition phase of any major program. According to Army Spokesman Pat Mehney:
There are no available statistics for how much fuel savings the entire FCS fleet will achieve once it arrives. The Army estimates that an FCS heavy brigade combat team will consume 29 percent less fuel than its current counterpart, Mehney said. During a 1,864 mile mission lasting several days, a current heavy brigade combat team consumes an estimated 1.3 million gallons of fuel. But an FCS brigade would only consume 942,000 gallons, according to a simulation study conducted by Sandia National Laboratories. On a paved road, the FCS heavy tracked vehicle travels 1.66 miles per gallon. By comparison, the Abrams tank can go 0.52 miles per gallon.
FCS, with vehicles still in development, seems poised to shake things up a bit. I'm going to keep an eye on it, both in terms of its survival, as well as the extend to which is can design and deliver tactical systems which consume energy in a markedly more efficient manner. If it does, it will signal an important break with the past.
Photo of Army "Non Line of Site (NLOS) Cannon": Army FCS Program Manager site