Many years ago I watched a film (American, I think) where a family take their RV - motor caravan - on holiday. The parents are in the van and the hand brake is accidentally released, sending the vehicle over the edge of a cliff and crushing it below and killing both parents. The boy (about eleven or so) has to look after himself, eventually meeting a man who tries to look after him. Does anyone know the title of this film?

The Earthling