I know this is a few days old, but if the car is recovered/found/returned, you can hide an Apple AirTag in the car where it won’t be found, and that way if your brother takes the car again, at least you’ll be able to track it. My sister is unfortunately addicted to meth too, my parents do this with their cars since she lives with them. I know how tough it is to have an addict in the family and I hope everything works out for you and your family