The curfew law for her is as follows (this is taken directly from the law itself): Sec. 11-34(3) Curfew--Juveniles age 16 and older.
It is unlawful for any juvenile, on or after his sixteenth birthday to be present in, about or upon any public place or establishment in the city between the hours of 12:00 midnight and 5:00 a.m. of the following day.
(g) Public place
is any place to which the public or a substantial portion of the public has access and includes, but is not limited to, streets, sidewalks, alleys, rights-of-way, parks, playgrounds, or government buildings or facilities; vacant lots; and the common and/or parking areas of government buildings and facilities, schools, hospitals, apartment homes and complexes, office buildings, shops, malls, and
other establishments.Sec. 11-34(5). Exceptions.
The provisions of this section shall not apply to any juvenile who:
(a) Is accompanied by his parent or guardian;
(b) Is an emancipated minor;
(c) Is involved in an emergency;
(d) Has permission from his parent or guardian to travel to, or be in or at, a specific public place or establishment for a reasonable, legitimate and specific purpose;
(e) Is exercising First Amendment rights protected by the United States Constitution, including free exercise of religion, speech, and assembly.
(f) Is engaged in interstate travel;
(g) Is attending, or traveling to or returning from, an official school, religious or other civic or recreational event supervised by adults and sponsored by a governmental entity, a civic organization, or another similar entity that takes responsibility for the juvenile;
(h) Is engaged in employment activity, or traveling to or returning from such activity; or
(i) Is on the sidewalk immediately abutting the juvenile's residence.
So, to sum up, the curfew law does apply even when she is in her vehicle, and being accompanied by an individual over 18 is not enough...it must be a parent or guardian, or she must be engaged in one of the other activities outlined above under the "Exceptions" section, such as traveling from work or a school activity.
Hope this helps clear things up.