Well, most crashes are preventable, even mechanical failure to some degree.
This rainy morning, as I was descending down a 10% grade coming up on an intersection, I observed two cars: grey Pontiac G5 being followed at about 3 feet distance by a large black Dodge Ram 1500.
Both vehicles were in the middle lane of a 3 lane street, where traffic 'typically' travels around 60km/h.