They are using off-the-shelf brushless motor controllers (from what I can gather) and off-the-shelf brushless motors. There are many makers of ESCs with your requirements including from the now-ubiquitous HobbyKing, both sensored and sensorless (for RC car applications) including this one:
http://www.hobbyking.com/hobbyking/store/__17234__Hobby_King... which will do variable engine braking as well.
Our motor control ESCs, remote control electronics, battery management systems, and software are entirely custom. Off-the-shelf RC parts aren't smooth, reliable, safe, or quiet enough.
JohnnyCowboy's concern about early motor failure from the sideloading--do you have estimates on the mean mileage between component failures, and how much replacements would cost?
