The Bickle '76 is visually distinguishable by its red paintjob, supercharger, solid grille (as opposed to the standard 'egg-crate' grille seen on regular Taxis), and the pair of fluffy dice hanging from its rear view mirror. Occasionally, this vehicle will spawn without a taxi sign on the roof, resulting in a much sportier look. However when the player starts the Taxi Driver (with no taxi sign), the roof will glow, which is possibly a bug or glitch. The name of the taxi is taken from Travis Bickle, the lead character of the 1976 Martin Scorsese film Taxi Driver, portrayed by Robert De Niro. Its location outside Mean Street Taxis may be an allusion to this -- Mean Streets was the name of an earlier Scorsese/De Niro collaboration.
There is a glitch in the PlayStation 2 version in which the Bickle may not immediately begin spawning after completing the side mission. It may be necessary to let a few days pass in the game before it begins showing up.