Darwin is a MASTER escape artist.
He's opened windows, shot through legs, or slipped his lead/harness.
We've probably had to chase him half a dozen times.
Once you've caught up with them, DON'T chase them.
They turn it into a "chase me" game.
What you do once you've caught up with them.
Call to them to get their attention.
Sit on the floor and pretend that you are eating something really tasty.
Make loud. . . "Mmmmmm, NOM" type noises.
The thought of food will draw them to you and. . voila snagged.
Works every time.
However you might still have a 5 mile run to catch up with them first.