Searched, didnt find anything, so assuming im the first.
Basically i joined WG, but we were losing. When we were about 1 min until losing my AV queue popped so i took it. After AV i appeared back in WG with battle over, BUT i still had the rank that allowed me to use all vehicles.
Persisted through logout.
I decided to wait until next battle, logged in in 2 hours and took part in the battle. And was able to get the siege engine right away.
Imba fast WG go!
Edit: while waiting i also moved around and it persisted through zoning as well.
And heres a pic.