Hi there,
this will be old news but I don't remember having read about it:
On our server at least some vehicles (I witnessed a Vodnik_Medevac, yesterday) spawn on one of these small pylons when bought at Bash or Klen.
The vehicle then stands on its rear and typically the 'get in as driver' menu is not accessible.
I had a report of one player that managed to get into the vehicle and start it, leading to him being propelled 100m into the air :-)
Is this a known problem? Can you delete the pylons from the map or move the spawn point?