In my machine elements class, we had a project to design an RC Car, optimizing the drive train and steering with concepts we learned in the class. My team ended up getting 1st place out of 30+ teams!
The 3-wheeled design is to prevent rear wheel slippage which can result in unstable steering and wasted energy. Normal cars have a differential to prevent this, but that's difficult to accomplish on a small scale and limited budget. The pulley on the right drives the rear wheel from a high-speed brushless motor at the optimal gear ratio.
After the competition, the car was taken to a few outreach events with the UT robotics club. The picture below is from the 2018 Maker Faire Austin, where we let kids drive around our robots all over the convention floor!