I remember that this story was set in countryside in America
- Protagonist is male
- He lives on a farm when new neighbours arrive; there are 3 of them - man, woman and their daughter.
- Those neighbours fix previously-abandoned farm quickly and become efficient workers.
- Later a reporter arrives to investigate this area, since it had shown higher yield that anywhere else
- Reporter suspects that there is something fishy about the recently-arrived family, and when he tries to leave town - he cant, since his car gets magically turned around in an unnoticeable fashion halfway down the road.
- It is strongly implied that the new neighbours are alien, since their car, otherwise looking broken contains a box-like peace of shiny metal instead of engine and a smoke generator-thingy like in toy trains.
I think this may be a Simak story, but I was unable to find the name.