Hazrat Mahdi (as) is moderate of virtue and excellent of creation... HIS STEED WILL SHINE LIKE A FULL MOON. HE [HAZRAT MAHDI (AS)] WILL GO AT THE HEAD OF THE MOST AUSPICIOUS COMMUNITY. They are enfolded by Allah’s religion; they will seek to approach Allah with him...
(Sheikh Muhammad bin Ibrahim Nomani, al-Ghaybah al-Nomani, p. 171)
In the hadith it is suggested that “cars” will be one of the technical vehicles available in the time of Hazrat Mahdi (as), and that these will have headlights and interior lighting. It appears from the information provided in the hadith that the headlights of Hazrat Mahdi’s (as) car will also shine brightly.
In addition, the fact that it is emphasized in the hadith that Hazrat Mahdi’s (as) steed will shine “like fullmoon” is an astonishing detail. The term indicates a large, oval and entirely illuminated source of light in Hazrat Mahdi’s (as) car, a detailed description of its headlights.
The words “He will go at the head of the most auspicious community” indicate that Hazrat Mahdi (as)’s car will be at the head of a convoy consisting of his own students.
Alternatively, the term “he will go at the head” may refer to Hazrat Mahdi (as) being seated at the front of this vehicle.
Aban ibn Taglib says: I heard Imam Jaffar Sadik say: “It is as if I see the Qaim [Hazrat Mahdi (as)] at Najaf in Qufa ... HE [HAZRAT MAHDI (AS)] WILL THEN MOUNT ON A BLACK AND WHITE STEED WITH THE SPACE BETWEEN HIS EYES SHINING LIKE A LIGHT...” (Sheikh Muhammad ibn Ibrahim Numani, al-Ghaybah al-Numani, Part 19, Hadith no: 4; http://www.al-shia.org/html/tur/books/book1/027.htm#link28)
This hadith indicates two headlights on the two sides of the car and that Hazrat Mahdi (as) will use black and light-colored cars.