A car that you don't drive but you leave it in front of the house. This is a yard car. You leave it in front of the house to make it look like someone is home. Unlike an earlier definition, this car must be believable, that is no flats, no grass growing under it, or other indications that it might not be in use. Wash it. Move it, that is, push it at least ten feet every few days. To friends you don't entirely trust, refer to it as "Bubba's Volvo" and mention Bubba being on probation.
Neighbor: Hey, Jim. I dropped by the other day to borrow your weed eater, which I'll return with the hedge trimmer. That Volvo was here, but nobody answered the door.
Resident: Oh, yeah. That's Bubba's Volvo. He drops by once in a while, especially when he needs to avoid his probation officer.
Neighbor: Lemme get that trimmer for you. (exit neighbor).
Resident (muttering to himself):
Yard cars are a good thing.