The mini-cab app has a modified Ford car which has an Uber logo on the side and a large box on the roof, according to reports in the local newspaper this month.
Following the rumours Uber confirmed that the car was the work of the firm's Advanced Technologies Centre, which focuses on robotics in transportation.
"This vehicle is part of our early research efforts regarding mapping, safety and autonomy systems," Uber spokesperson Trina Smith told the Pittsburgh Business Times.
The research centre uses talent from nearby Carnegie Mellon University to develop driverless car technology, in a bid to beat the likes of Google and Nissan, firms that are investing in autonomous car projects and partnering with the likes of NASA.
Google have tested both the technology and a proprietary vehicle that can control itself on the road this month. Some reports claim the search giant is also working on a ride-sharing app to compete directly with Uber and Lyft - another taxi app that is popular in the US.
This may explain why Uber is making a multi-billion bid for Nokia's mapping software, Here, as it currently relies on Google Maps.
One main advantage to driverless cars is the claim it will help make roads safer, a point Google appears to be proving. The company claims its vehicles have been involved in only 11 accidents since testing began and only one was caused by the car.
Chris Urmson, director of Google's self-driving car program, revealed that the most challenging aspect of developing this technology is programming these cars to account for the irrational choices and behaviour that human drivers make on the road every day.