Any vehicle or drone that has an autopilot can be attacked from the Matrix.
A successful sleaze hack against an autopilot is sufficient to issue it one command of about one or two sentences length or to Jump In to it. If you issue a command, that command can be superseded by the vehicle’s or drone’s owners or occupants when they notice, of course. If you Jump In, the drone or vehicle is yours to command unless/until you are overridden (see “control hierarchy” below) or somebody crashes your connection.
As usual, if the drone or vehicle is networked in a PAN, WAN, or s-PAN, that has to be dealt with (sleaze or cybercombat hacked) first.
If a vehicle or drone’s autopilot is crashed in cybercombat, then the autopilot and navigation is disrupted, but the occupants can still use manual controls to take over. Even if they don’t, then a backup failsafe system will attempt to bring it to a safe halt. (It might fail though, they’re quite basic.)
Drones are not smart and are easily confused by messing with their Matrix traffic. Deckers attempting DoS attacks against them take +2 on their rolls.
A single successful sleaze hack roll is enough to get a parked vehicle to unlock itself, disable the autopilot, and then activate manual controls. It can then be stolen. However, this comes with some severe caveats that kick in as soon as the theft is noticed:
Some vehicles are throwbacks and lack any sort of autopilot. They cannot be hacked. They can be stolen and hotwired with the Thievery skill.
A small number of prestige throwback vehicles have been retrofitted with rigger interfaces, however. They still cannot be hacked, and a direct cable connection is required in order to Jump In to thm.
If multiple entites are competing to control a given vehicle or drone at the same time, there’s a hierarchy which determines who wins:
Hence, hacking an autopilot and issuing it commands can be overridden by anyone inside the vehicle who can access the physical controls. A rigger can jump into the vehicle remotely, but a competing rigger inside the vehicle can usurp them with a direct cable connection.