I've found if you put them in a crafted Nest it will save them. But, still the issue of when you log out, they disappear from your selection wheel. You then have to go to the Nest and find the one you were using and pull it back out. It will then show up in your wheel.
My issue is if you logout, crash, or even die, the buggy will be back in the Nest and not linked to you anymore. You then have to go BACK to the Nest and pull them out yet again, which is a pain when you rode it all the way across the map, just to crash, come back in, and walk all the way back just to get your ant again.