Sometimes it seems our faith in technology — or at least, our willingness to shell out big money for it — is boundless. A report on so-called self-driving cars, appropriately titled “Reality Check,” ought to bring us back down to earth.

Issued by the Insurance Institute for Highway Safety, the report is the result of testing five different makers’ cars equipped with automatic pilots. The devices allegedly can operate vehicles safety without any help from drivers.

They can’t, according to the IIHS. Each and every one of the five systems tested was found to be seriously flawed. “We have found situations where the vehicles under semi-automated control may do things that can put you and your passengers at risk,” explained IIHS official David Zuby.

Red flags already have been seen. During the past year, two automated Tesla cars were involved in fatal crashes.

Theoretically, it ought to be possible to build an automated vehicle. Local and state officials tempted to permit use of such cars and trucks on their highways should remember that “theoretically” is a big word.