I vaguely remember hearing that the leading candidate for the next US tank is a hybrid. Not even a joke, Diesel-Electric drive provides instantaneous torque benefits over straight diesel. Add in the potential benefits of being able to power electronics or go short distances without the noise of an engine compromising stealth and it's a very real benefit.

Edit: Found an article for anyone interested.

>The AbramsX replaces the M1's efficient but notoriously fuel-guzzling AGT 1500 gas-turbine engine with a hybrid-electric engine more reminiscent of a Toyota Prius than conventional tank power plants.

>General Dynamics claims the new engine slashes fuel consumption by 50%, improves reliability and ease of maintenance, and allow the tank to operate its electronics — and even perform some limited movement — using quieter battery power.