Alright, as the title goes. We pay for our cars, they completely belong to us. People just come and steal them when we're chasing a suspect (sending it to storage would be totally disturbing because if the suspect flees away, we'll have to wait for it to come back, and bla bla). Other people should not be able to use any person's personal vehicle, which will make it fully belong to them, I've been into this issue many times, people often steal my vehicles when I'm inside an interior, or busy in something. They either destroy it to make me pay the fee, or pop it's tyres and damage it. I don't know if this has been ever suggested before.. I checked and couldn't find any, so here we go. I suggest that there should be a popped up text when people are trying to enter other people's personal vehicle, like 'this is Parzival's personal vehicle, you are unable to enter it', just my point of view, rest's on ya.
Peace out