def is_passenger_car(df):
    """Return if vehicle is a passenger car, per NHTSA convention."""
    yr = df['YEAR']
    body = df['BODY_TYP']

    return ((yr.between(1975, 1981) & body.between(1, 9)) |
            (yr.between(1982, 1990) & (body.between(1, 11) | (body == 67))) |
            ((1991 <= yr) & (body.between(1, 11) | (body == 17))))