Nope I couldn't find it either, looked in base ONSVEhicleFactory, SVehicleFactory.
The spawn protection immediately drops if someone enters the vehicle.
Same with player protection it drops if you fire, often I've found I've reactively fired before even thinking when I spawn in and getting shot at.
Vehicle spawn protection
Re: Vehicle spawn protection
I’ll start recording when it happens, but sometimes it seems like I get almost no spawn protection, while other players seem to get spawn protection that lasts for several seconds. Just like how some players can spawn into a node that’s being hit or has already been destroyed, but I’ll try spawning at a node that’s not even flashing and the server says NOPE!
“Never argue with stupid people, they will drag you down to their level and then beat you with experience.”
― Mark Twain
― Mark Twain