“It will evolve from where that was, but it's the same basic technology, sized and scaled to meet the new requirements,” Signorelli says.

BAE is pushing forward in its GCV bid with a series drive train, betting on increased fuel efficiency, mobile power supply and the design flexibility afforded by getting away from a traditional mechanical model.

Its drive concept for the 70-ton giant centers on two in-line six-cylinder diesel engines from Germany/U.K.-owned Tognum, a traction drive system from Qinetiq and a Saft lithium-ion battery pack which is a variant of those flying on the F-35. In a series design the diesels are not connected to the transmission but act as generators for the battery, which runs two electric motors producing about 700 hp each. The electric motors drive the tracks, providing instant torque at zero rpm.

The series design is part of BAE's aim to deliver a modular platform, which is one of the four priorities for the GCV, the others being force protection—accounting for the bulk of the vehicle—capacity for a nine-man squad and a seven-year window for the first production unit. “The hybrid-electric is lighter and smaller, so we can reduce the volume under armor; or conversely are able to add more armor or force protection with no penalty in terms of the drive train,” Signorelli says. “The engines are more manageable in terms of packaging. We don't have to place them near the transmission, because the only connection between the two is the power bus.” Power from the batteries is an added bonus—the design means each vehicle can deliver up to a megawatt of electricity, enough to power 1,000 homes.

Still, Signorelli expects a tough competition over the next 18 months. Details on GD's bid have yet to fully emerge, while U.S. budgets are under pressure and there is an ongoing debate on Capitol Hill about the utility of heavy vehicles in asymmetric warfare. But indications are that whatever the outcome on the GCV, hybrid-electric designs will continue their slow but steady march into the production line.