For U.S. railroads, hauling passengers is an expensive proposition: it runs them into the red by some $700 million yearly. Last week the nation's No. 1 automaker showed off an air-conditioned train that could put the money-losing passenger lines back in the black.
On one exhibition run, General Motors' 400-passenger Aerotrain streaked over the Pennsylvania Railroad from Washington to Philadelphia in two hours—as fast as the crack Congressional Limited. The same day, another Aerotrain rolled out of Chicago over the tracks of the New York Central and highballed 284 miles to Detroit in four hours, an hour better than the...