You know what would probably be awesome? Mobile energy sources! When the going gets tough, all your energy activates wheels/legs/rollers and scoots away with your army!
Fast mobile solar trucks for light vehicles!
Jumpy jumping Windmill bots!
Floating Amphib tidal bots!
Tanky and explosive Mobile Fusions!
Giving players the option to build a less efficient but more mobile economy could lead to all sorts of shenanigans, it was pretty awesome in Imperial Winter, as the four or so people who played that game might testify!