What DIY Drones were a half-decade ago, DIY autonomous cars are now. I'm part of the Self Racing Cars group in the SF Bay Area, who are building and racing autonomous vehicles from 1/10th scale to go-karts to full-size cars (Ford Fusion is the go-to vehicle, since it's the cheapest car that's fully drive-by-wire and can easily be made autonomous).
Above is the autonomous go-kart that Autodesk CEO Carl Bass and I built, with autonomy provide by a Pixhawk and the APM:Rover code, plus custom computer vision processing on a RaspberryPi. (The gorilla is for ballast -- and looks)
If you're in the Bay Area, you can join the Meetup group here. First hackathon/meetup is on Oct 30 in Berkeley.