I hope everyone realizes that there are plenty of autonomous 'vehicles' out there. Right now. With limited security. Most single engine planes have highly developed autopilots. The hard part is getting one to take off autonomously. That could be solved by parachuting out after you reach level flight. Steal a Cessna 185 with your typical Garmin AP. Land it in some field, fill it up and take off at night. Jump out and off the plane goes. You won't get to the White House or the Capital building but your could probably hit some random oil refinery near a city.
Even little boats now can install sophisticated autopilots that will drive the boat anywhere you can find on a map. And a 20 foot boat could hold a whole bunch of diesel and fertilizer. My 22 footer can drive out of it's slip and wander off 100 miles without any human intervention whatsoever. The only limitation is that the AP doesn't control the throttle. But a very simple hack could since it it has drive-by-wire controls. With essentially no security. Nobody tracks little boats except in a few very congested waterways.