The car used by Will Smith's character is a concept car called Audi RSQ, which was designed exclusively for the film and includes special features suggested by director Alex Proyas.
No re-shoots were required, a rarity for a movie as big as this.
For the character of Sonny the accused robot, the effects team used the same process that was used to create Gollum in the Lord of the Rings trilogy, with Alan Tudyk providing the body movements and voice for Sonny.
The corporation in the movie is called "US Robotics." A company under that name exists in the real world too (presently "USR"). Both got the name from Isaac Asimov's works and its fictional company "US Robotics and mechanical men."
Sonny is not walking in step with the other robots as he's being escorted, which subtly sets him apart as unique, even during the most mundane actions.