What he did is impressive. But the results are not that outlandish for a talented person.
1) Hook up a computer to the CAN-Bus network of the car [1] and attach a bunch of sensor peripherals.
2) Drive around for some time and record everything to disk.
3) Implement some of the recent ideas from deep reinforcement learing [2,3]. For training, feed the system with the oberservations from test drives and reward actions that mimick the reactions of actual drivers.
In 2k lines of code he probably does not have a car model that can be used for path planning [4] (with tire slippage, etc.). So his system will make errors in emergency situations. Especially since the neural net has never experienced most emergencies and could not learn the appropriate reactions.
And guess what, emergency situations are the hard part. Driving on a freeway with visible lane markings is easy. German research projects autonomously drove on the Autobahn since the 80s [5]. Neural networks were used for the task since about the same time [6].
[1] http://www.instructables.com/id/Hack-your-vehicle-CAN-BUS-wi...
[2] http://arxiv.org/abs/1509.02971
[3] http://arxiv.org/abs/1504.00702
[4] http://www.rem2030.de/rem2030-wAssets/docs/downloads/07_Konf...
[5] https://en.wikipedia.org/wiki/Eureka_Prometheus_Project
[6] http://repository.cmu.edu/cgi/viewcontent.cgi?article=2874&c...