On the 40-mile stretch of highway between Ann Arbor and Detroit, even housewives in curlers pretend they are Mario Andretti. But one morning last week drivers revving up for the dash to Detroit found all lanes blocked by a trio of cars traveling abreast at 55 m.p.h., the legal speed limit. Behind the wheels were Stephen W. Long, Elizabeth Ann Lipski and Bruce Nielson, three friends who had taken it upon themselves to enforce the law. Their cars were decorated with signs reading GAS SHORTAGE and STAY ALIVE AT 55.
The vigilantes of Interstate 94 almost produced the opposite effect. As traffic...