Peter, when my wife and I were dating long ago her family had two white German shepherds, King and Prince.
Every time I visited Price would jump into the back seat of my Mustang convertible wanting a ride.
One day Prince got out of the fence and went exploring. I did not know it but when I saw him a mile or so from his home, snooping around the post office of our little town I new he was AWOL.
I whistled once and he bolted to the Mustang at a dead run at a dead run and jumped in.
For his wise decision I drove him around for half an hour as a reward.