A passenger automobile is any automobile (other than an automobile capable of off-highway operation) manufactured primarily for use in the transportation of not more than 10 individuals. A medium-duty passenger vehicle that does not meet the criteria for non-passenger motor vehicles in § 523.6 is a passenger automobile.
49 C.F.R. §523.4
Sec. 301, Pub. L. 94-163, 80 Stat. 901 ( 15 U.S.C. 2001 )