Once I’ve noticed that almost all my infantry units have their own trucks, even those that may have benefits from not having them, like paratroopers or mountain infantry. And there is good reason beyond it: I want my army to be as mobile as possible and infantry unit without truck is not mobile at all. However, in some scenarios it can be useful to mount paratroopers on plane or have mountain infantry unmounted, like it was in GC’39 Norway missions. Of course I can “upgrade” my infantry and delete their trucks and then in next scenario buy them again, but I find it very annoying and I also need to pay additional prestige for such operation.
So, my suggestion is to allow player to left infantry trucks in reserve at no cost. This is logical to me, since I can left any unit in reserve and not pay anything for it, but I have to pay additional 50/100 prestige for leaving truck or halftrack behind. It also could convince players to use infantry without trucks where it is needed.