This feature has worked for me, with no intervention required.
But it can also be unintentionally funny, as the widget throws up useless responses because of the way it works and the data it has.
When you're not in proximity to the car that your phone is paired with, and find yourself in a different location, it seems to lack any smarts to figure that out. When I was out and about with another car, and left the paired car at home, it helpfully told me my car is parked 12 miles away.
Even when you are close, like at home, it can act amusingly. I watched the other night as it first told me the car was on the same street as my residence, then 1000 feet away, then 100 feet away, all within the span of 20 seconds as kept working on getting a fix.
Behind the scenes, all it simply appears to do is compare your phone's current location with the location where the phone last had a paired connection. No logic to analyze or provide a filtered response. I suppose the next time I hop on a plane, it will let me know that my car is parked hundreds, if not thousands of miles away.
This isn't a complaint. I just find it amusing. It's a nice feature, but the implementation still needs some work.