[Moonrunner]

We cannot seem to find in the core rulebook anywhere how a Rigger can hack into an enemy vehicle.

Can you all help us on how this works, please?

[Stainless Steel Devil Rat]

Until Rigger 6 comes out, the way to hack any device (vehicles included) are covered in the Matrix Chapter.

In the meanwhile, you could assign a rating to the door locks, and have someone pick it.  Then assign a B/R threshold to hotwire the car, and then there's rules already given to shut off wireless (so the police don't just shut you down remotely).

See also this thread and this one, too.

[ZeroSum]

It would also help to know what you are trying to accomplish.

Open the doors to get at something inside? Stop it from moving? Make it move?

All of the above can be accomplished with existing Matrix actions, like Stainless Steel Devil Rat points out.

If you are trying to steal it, that's a different story.