Would you mind elaborating? Why would it not be okay to drive your own car once you find it? Sure you might get stopped by police, but should be able to explain and prove the ownership.
Why ask me? GP is the one who found the car but had it re-stolen, ask them why they didn't recover it.
There was also a recent HN submission where a blog post author used a GPS tracker to find their car but relied on the police instead of recovering it themselves, with predictable results. https://news.ycombinator.com/item?id=30442044
