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.