When you load a vehicle, it doesn't change the chassis color.
I noticed that, but the saves are just for bricks, since other mods can change the chassis properties.
Also, you can ride in someone else's vehicle without any trust.
It's the same as any vehicle, but I assumed it required trust on a default install. I'll add this to the OP:
http://forum.returntoblockland.com/dlm/viewFile.php?id=25Truce, are you still here?
Yeah, you've got a lot of add-ons though. My suggestion would be to turn all the ones not on RTB off (including this one) and see if you can activate bricks. You most likely will be able to, since RTB usually doesn't have broken add-ons, so it will narrow down which ones could be causing it (out of the ones you disabled).