Anyone know? - motor rifles

[Volcano Man]

Yes, correct. I is just a graphic. Think of it as chrome, the majority of those Motorized Rifle units didn't have their own transport at all, and they road around on tanks. We don't have the ability to attach/carry units with other units in PzC, so you just get the picture to remind you that they are desant tank riders. ;)

But more importantly, in the ALT scenarios their movement type did change to halftrack while in T mode, as you said, to represent the better mobility than trucks.  They aren't tracked, because IIRC, that would turn the unit into vehicles instead of men. This might be officially replicated in the latest PzCs too, I cannot recall though.