After fixing it up, if your Sim parks it at a public venue, other Sims
will interact with and/or steal it.
Please keep it parked at home, folks
I already lost one and was about to lose another, when I spotted the perpetrators. I clicked on the car and via NRaas's MC, I sent it to my household inventory. The offending Sims remained sitting in the air and continued to interact. Muah!