How to make a Lego Mindstorms ev3 self driving car?
I don't have a Lego EV3, but I have created a self-driving car with my NXT brick. I found the instructions from nxtprograms.com, but they are for the NXT. (I'm sure that you can adapt them for the EV3 though). The program is also for the NXT, but nxtprograms provides enough comment blocks that I think you should easily be able to build your own program with the EV3 software.

Here are the instructions:
http://nxtprograms.com/NXT2/explorer/index.html