No it is not idiomatic. Under normal circumstances only a sentient being can run away. The only sense in which a motor vehicle can be said to run away is if the driver of the vehicle leaves it parked on a slope having forgotten to apply the brakes.
The rails were froze, the wheels were cold, then the air brakes wouldn’t hold,
And Number 9 came roaring down the hill — oh! The runaway train came down the track and she blew.
The runaway train came down the track and she blew. Children's song http://www.madacademy.com/02/2012/childrens-song-lyrics/skip-song-lyrics/the-runaway-train/