Need Two Vehicle Slots for One K-Drive?

[Astral-Vine]

I bought a vehicle slot so I could level up a K-drive.  I don't see any reason to have all four at the same time since they're all the same except for looks.  It won't let me sell the K-Drive I mastered in order to build another one without buying another second vehicle slot.  So basically, I have to buy two vehicle slots just to get rid of one.  Since there's a default K-drive in the first place, if I sell the one I mastered why can't it go back to that?   I'm going to literally be getting a new K-Drive seconds after selling the first one.  I have no use for another vehicle slot since I have all archwings.  It's a waste of plat and if it was on purpose i hope they fixed it.