Roads would be neat, give the GVs 2x speed bonus while on the road. Be careful getting off the road though.
What about the AI resupply convoys? It has been a long time, I don't know if it will still happen, used to be the convoy would run right over a tank and kill it...
It would add a touch more realism, be neat if the roads had choke points like bridges that could be knocked out. Use the resupply to fix it. Of course you could by-pass the bridge, taking additional time and risk.
Make for some interesting armor battles...