If the flying death machines are going to make that much noise, it should be fairly straight forward to use a few microphones and CNC machine guns to locate and shoot them down.
Phalanx was successfully adapted to shoot down mortar shells in Iraq (C-RAM.) If it has a radar return Phalanx can probably kill it. This sort of weapon could be adapted with infrared or other anti-radiation sensors as well.
I think the answer to defending against offensive UAVs is defensive UAVs. Just today a story[1] appeared about a USAF Reaper shoot down of another UAV. Supposedly a first.
I could see it being hard to aim at them accurately enough to hit, iirc the CIWS systems are radar aimed for missle defense. Depends what kind of UAV we're talking about an antipersonnel UAV could probably present a small enough radar signature.
You joke, but IS and JaN/JFS in Syria used the piloted versions of these: SVBIEDs aka suicide car bombs. Soviet APCs were abundant enough that they could even deploy armored variants.
They were extremely effective in combat, and called the "poor man's cruise missile" by analysts. Here's a video of a strike; note that they were often used in as the opening salvo of combined arms attacks. https://www.youtube.com/watch?v=AZBAU_TTZ-4
Why do they need to be self driving cars? They’ve already proven effective using suicide drivers. They’ve also proven RC quadcopters are an effective delivery mechanism as well. Combine the RC aspect with the car, no fancy AI needed.
Of course there’s an aspect of their ideals that glorifies suicide so maybe they’ve already thought of this but just prefer to keep the suicide route.
Because a quadcopter is meant to be controlled remotely, while a traditional car isn't, so retrofitting it for remote control is likely time consuming and error prone (ever watch one of the mythbusters episodes where they rig up a car for RC?).
Self driving cars already have everything required to control the car built in. They just need to hijack the existing controls and hook it up to a RC system (or just tell it to drive to location using internal controls).
That's a good point. A stock standard autonomous vehicle ought not be able to. One wonders at how much modification would be necessary to override or bypass any software / hardware lockouts.