Fred, the FTC regs specifically apply to units sold for "home entertainment purposes" and therefore don't regulate automotive equipment. In 1998 the Commission took some evidence relating to expanding the coverage to include mobile units, but determined that there wasn't sufficient evidence presented to support the proposal.
There are no regulations which have the force of law, such as those which should make us confident of the accuracy of home audio amplification equipment power ratings , which would give similar assurance as to automotive equipment. There is a voluntary regulation(CEA-2006-B)for mobile equipment proposed by the Consumer Electronics Association which some manufacturers follow, but of course this isn't law. A brief discussion of this can be found
here .
