Beware, The Thieves are Out

[husker boxster]

So let's drop the politics and get back on track...

OP, if someone is pouring paint in your gas tank, among other things, it sounds like you have someone with an axe to grind vs common thieves. Nice of you to house your GF's mom, but you might suggest to her these hooligan adventures are costing you money and unless she wants to foot the bill, the solution is to get your car in the garage. I know that's easy for me to say in Neb behind my keyboard, but it's worth broaching the topic with her. Maybe she isn't the best driver and is concerned about hitting your car if it's in the garage. Offer to drive it in or out for her. There has to be some sort of accommodation that could be made.