Stray cats keeping warm in cold weather?

Why not set up another warm bed, away from your cats bed, in your garage. Maybe put it close to the door. Set out an extra bowl of food and some water, near the extra bed. Don't use warm water, it actually freezes faster than cold does. Cats are attracted to somewhat enclosed spaces, like little caves. If you can make the bed sort of wrap around a space just large enough for a cat to fit inside, you may get it to come in. It will be like a bed & breakfast for cats.